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mechanics
American Academy of Mechanics
Academia Americana de Mecanica
Volume 31, Number 3-4
March-April 2002
(references in the form \M28(3-4)" indicate the last time the
Journal was cited in mechanics: v. 28, n. 3-4, in this case.)
Letter from the Editor
Position Openings
Announcements
Selections of the Editor
Application for Membership
mechanics Contents
Acta Materialia
Acta Mechanica
AIAA Journal
Applied Mathematical Modelling
Applied Mathematics and Mechanics
Applied Mechanics Reviews
Archive for Rational Mechanics and Analysis
Archive of Applied Mechanics
Archives of Mechanics
Communications on Pure and Applied Mathematics
Composites Part A: Applied Science and
Manufacturing
Computational Mechanics
Computer Methods in Applied Mechanics
and Engineering
Computers & Fluids
Computers & Structures
Earthquake Engineering & Structural Dynamics
Engineering Fracture Mechanics
Engineering Mechanics
Engineering Structures
European Journal of Mechanics A-Solids
European Journal of Mechanics B-Fluids
Experimental Mechanics
Experiments in Fluids
Fatigue & Fracture of Engineering
Materials & Structures
Finite Elements in Analysis and Design
Flow, Turbulence and Combustion
IMA Journal of Applied Mathematics
Industrial Mathematics
International Journal for Numerical and
Analytical Methods in Geomechanics
International Journal for Numerical Methods
in Engineering
International Journal for Numerical Methods in Fluids
International Journal of Damage Mechanics
International Journal of Engineering Science
International Journal of Fatigue
International Journal of Fracture
International Journal of Heat and Fluid Flow
International Journal of Heat and Mass Transfer
International Journal of Impact Engineering
International Journal of Mechanical Sciences
International Journal of Non-Linear Mechanics
International Journal of Plasticity
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International Journal of Pressure Vessels and Piping
International Journal of Solids and Structures
Inverse Problems in Engineering
Journal of Applied Mathematics and Mechanics
Journal of Applied Mechanics
Journal of Biomechanical Engineering
Journal of Biomechanics
Journal of Composite Materials
Journal of Computational and Applied Mathematics
Journal of Computational Physics
Journal of Elasticity
Journal of Engineering Materials and Technology
Journal of Engineering Mathematics
Journal of Engineering Mechanics
Journal of Fluid Mechanics
Journal of Fluids and Structures
Journal of Fluids Engineering
Journal of Intelligent Material System and Structures
Journal of Microelectromechanical Systems
Journal of Non-Newtonian Fluid Mechanics
Journal of Reinforced Plastics and Composites
Journal of Sound and Vibration
Journal of Strain Analysis for Engineering Design
Journal of the Mechanics and Physics of Solids
Journal of Thermal Stresses
Journal of Vibration and Acoustics
Journal of Vibration and Control
JSME International Journal Series A
JSME International Journal Series B
JSME International Journal Series C
Mathematics & Mechanics of Solids
Meccanica
Mechanics of Composite Materials and Structures
Mechanics of Materials
Mechanics of Solids
Mechanics of Structures and Machines
Mechanics Research Communications
Medical Engineering & Physics
Nonlinear Dynamics
Prikladnaya Mekhanika
Probabilistic Engineering Mechanics
Proceedings of the Royal Society of London, Series A,
Mathematical, Physical and Engineering Sciences
Quarterly Journal of Mechanics &
Applied Mathematics
Quarterly of Applied Mathematics
Rheologica Acta
Shock and Vibration
SIAM Journal on Applied Mathematics
Structural Engineering Earthquake Engineering
Structural and Multidisciplinary Optimization
Studies in Applied Mathematics
Technische Mechanik
Theoretical and Applied Fracture Mechanics
Thin-Walled Structures
Wave Motion
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mechanics
provides its readers with news in the eld of theoretical and applied mechanics, and
serves as a forum for the presentation and discussion of issues related to the development of the
science and profession of mechanics. Opinions expressed are those of the authors and do not
necessarily reect oÆcial points of views of AAM or the institutions with which the authors are
aÆliated.
mechanics
Editor:
Horacio D. Espinosa (Northwestern University, U.S.A.)
Gustavo Buscaglia (Balseiro Institute, Argentina), Eduardo Dvorkin (Univ.
Nac. de Buenos Aires, Argentina), Robert Haythornthwaite (Temple University, U.S.A), Dean T.
Mook (Virginia Tech, U.S.A), Djenane Pamplona (PUC-Rio, Brazil), G. Ravichandran (Caltech,
U.S.A).
Associate Editors:
The American Academy of Mechanics is a non-prot corporation incorporated in 1969 under the
laws of the Commonwealth of Pennsylvania. Its objective is to advance the science and profession
of mechanics, with particular reference to the countries of North, South, and Central America. It
aims to facilitate cooperation among mechanicists, to encourage recognition of achievements in
mechanics, and to promote public understanding of the work of the mechanicist.
(2001): M. Beatty (University of Nebraska), President and Chairman of the
Board; F. Moon (Cornell University), Immediate past President; D.T. Mook (VPI and State
University), Secretary; R.A. Heller (VPI and State University), Treasurer; L. Virgin, Director,
Region IA (Eastern USA); S. Datta (University of Colorado), Director, Region IB (Central and
Western USA); M. Paidoussis, Director, Region II (Canada); P. Kittl (University of Chile, Chile)
Director, Region III (Central and South America); R.M. Haythornthwaite (Temple University),
Publisher; C.W. Bert (Univ. of Oklahoma), Secretary to the Fellows.
Board of Directors
(ISSN 0076-5783) POSTMASTER: Send address changes to mechanics, Subscription
and Membership, ESM, MC 0219, Virginia Tech, Blacksburg, VA 24061 (Tel. 540-231-6871: Fax
540-231-2290). Editorial and Advertising: Horacio D. Espinosa, Northwestern University, 2145
Sheridan Rd., Evanston, IL 60208-3111 (Tel. 847-467-5989, Fax 847-491-3915). Membership in
the American Academy of Mechanics includes the subscription to mechanics.
mechanics
American Academy of Mechanics
Academia Americana de Mecanica
I
Letter from the Editor
May 12, 2002
Dear AAM members,
As you may have noticed, a year ago I started a section named “Selections of the Editor.” The idea
has been to bring to you information on new technologies, historical notes or as in this issue, articles
discussing the future of fast evolving technologies from a business perspective, see “The Future of
the Microprocessor Business,” by M.J. Bass and C.M. Christensen, as well as “The Opportunity and
Threat of Disruptive Technologies,” by C.M. Christensen. The insight provided by these articles is
very valuable in guiding our choice of research endeavors with the potential of having a significant
societal impact.
I would like to take this opportunity to invite you to contribute to Mechanics with articles written for
a general audience addressing important educational developments, historical notes on various
aspects of mechanics or other topics you may consider appropriate. The articles should be preferably
written in English but this is not a requirement. In fact, this issue contains an article entitled “About
the Path to Progress in Buckling Theory,” by L.A. Godoy, which is presented in Spanish. I hope that
this editorial decision will encourage more contributions from Central and South American AAM
members or readers.
Lastly, I would like to bring to your attention a letter I received from Dr. P.P. Nelson, Director of
the Civil and Mechanical Systems Division at the National Science Foundation, which is published
with her permission. Two issues discussed in her letter deserve special attention from you. The first
is the announcement of the retirement of Dr. Jorn Larsen-Basse. I am sure you all will join Dr.
Nelson in thanking Jorn for his excellent service and support to our community for the past many
years. The second is the announcement of a number of position openings in the CMS Division
including the Director position. As you may be aware, some people in the mechanics community
have expressed dissatisfaction and frustration with what is perceived as a low funding level in the
area of mechanics and as a result a low success rate of proposals submitted to CMS. Although this
perception may be argued, I would like to quote a statement by Dr. O. Dillon, which he recently
told me in regards to this issue, “… people in mechanics need to get more involved and serve in
various capacities at NSF in order to increase recognition of our field’s contributions and its societal
impact.” I am sure you will agree with Oscar’s reasoning; hence, I urge you to become involved and
submit nominations to Dr. Nelson.
Best wishes to all and a special greeting to all the moms in our community.
Horacio D. Espinosa
Editor
II
POSITION OPENINGS
National Science Foundation
Civil and Mechanical Systems (CMS) Division
Greetings:
I would like to inform the mechanics community that Dr. Jorn Larsen-Basse, who served as a program
manager in surface engineering and materials engineering for many years, has informed NSF of his
intention to retire at the end of this calendar year. I encourage you to express your appreciation to Dr.
Larsen-Basse for his years of service to your community - he has done a wonderful job!
At this time, the Civil and Mechanical Systems (CMS) Division has vacancies for Program Managers in
the three Program areas, one of which is the 1633 program:
•
•
•
The Structural Systems and Hazards Mitigation of Structures (SSHM) Program (1637)
The Dynamic System Modeling, Sensing and Control (DSMSC) Program (1632)
The Solid Mechanics and Materials Engineering (SMME) Program (1633)
The link to the CMS web page is http://www.eng.nsf.gov/cms/ and descriptions of these opportunities can
be found through that page.
I expect that you know of colleagues who would be good candidates. Please consider and send the names
and contact information for those you wish to nominate to me ([email protected], 703-292-7018) or to the
CMS Search Coordinator (Dr. Richard Fragaszy, [email protected], 703-292-7011).
These positions are not limited to individuals who currently hold academic positions, so think about
anyone you might know in industry or in a government job as well as faculty members. The CMS
Division needs highly qualified individuals to manage existing programs and to expand the grant
opportunities we provide for Civil, Mechanical and related engineering disciplines. We all benefit from
having well qualified, enthusiastic staff in CMS.
In addition, we are advertising for the important position of George E. Brown, Jr. Network for Earthquake
Engineering Simulation (NEES) Equipment Project Coordinator. This position has been occupied by Dr.
Thomas Anderson, and he has informed NSF that he will be leaving this position during this summer after
two years of service. We thank Tom for his contributions, and encourage you to consider nominating
persons from academe or industry for this very important position.
The position of Division Director (currently my position) is also being advertised. We need your help in
identifying highly qualified candidates for all of these positions.
Please feel free to contact me if you have any questions.
Best regards,
Dr. Priscilla P. Nelson
Director, Division of Civil and Mechanical Systems
Directorate for Engineering
National Science Foundation
4201 Wilson Boulevard, Suite 545
Arlington, VA 22230
Tel: (703) 292-7018 (direct) or 292-8360 (general)
Fax: (703) 292-9053
[email protected]
III
Civil Engineering
School of Engineering and Applied Science
Department Chair Position
The University of Virginia School of Engineering and Applied Science invites applications for
the chairperson of the Department of Civil Engineering. The University of Virginia has
approximately 18,000 students pursuing degrees in nine colleges and professional schools,
including the School of Engineering and Applied Science (SEAS). The University of Virginia is
consistently ranked as one of the top public universities in the country. The School of
Engineering and Applied Science has approximately 2,000 undergraduate students, 600 graduate
students, 150 tenure and tenure track faculty members in nine departments, and conducts
approximately $40 million per year in externally funded research programs. The Department of
Civil Engineering has more than 150 undergraduate students, 75 graduate students, and 15
faculty members. The department offers B.S., M.S., M.E., and Ph.D. degrees in civil
engineering. The department has undergone significant growth and programmatic evolution. The
department is implementing a new undergraduate curriculum, actively expanding its graduate
research program, and is engaged in multi-disciplinary programs with other departments,
schools, and universities. Active research programs exist within three main thrust areas:
environmental and geo-environmental engineering; structural engineering and applied
mechanics; and transportation systems, operations, planning, and safety. We seek a chairperson
who can provide leadership for a department committed to excellence in teaching, research, and
service, guide the growth of new promising directions, and visibly enhance the department’s
national stature.
Requirements: Candidates must have an earned doctorate in an appropriate discipline and an
outstanding record of scholarship and research achievement. Candidates with exceptional
credentials will be considered for an endowed professorship. Applications will be reviewed as
they are received and until the position is filled.
Interested Candidates please submit a letter of application to:
Professor James H. Aylor, Search Committee Chair, Ref. #5954, School of Engineering and
Applied Science, Dept. of Electrical & Computer Engr., University of Virginia, 351 McCormick
Road, P. O. Box 400743, Charlottesville, VA 22904-4743; Email: [email protected]; Phone:
434-924-6100.
Applicants are encouraged to visit the departmental website for more information at:
http://www.cs.virginia.edu/~civil/.
The University of Virginia is an equal opportunity, affirmative action employer.
IV
ANNOUNCEMENTS
AAM AWARDS NOMINATIONS
The Awards Committee of the American Academy of Mechanics
requests nominations for the following two awards
to be presented at the upcoming
ASME International Mechanical Engineering
Congress and Exposition in November, 2002
The 2002 American Academy of Mechanics
Outstanding Service Award
Preliminary nominations should consist of a one-page letter describing the outstanding service of the
nominee to the Academy as well as to the profession, along with a one- page biographical sketch of the
nominee, together with the names of at least three people willing to write letters of support in the event
that the Awards Committee requests them.
The 2002 American Academy of Mechanics
Junior Award
This award, which will be based primarily on research accomplishments, is open to mechanicians whose
highest degree was conferred after December 31, 1991.
Preliminary nominations will consist of a one-page nominating letter, one-page curriculum vitae, and re(or pre-) prints of the candidate’s best three papers. In the case of co-authorship of any work submitted,
the candidate’s contribution must be clearly and explicitly indicated in an attached note.
Please Note:
*
All preliminary nominations for both awards must be postmarked by August 1, 2002. Those that
do not arrive in a timely fashion will not be considered.
Once the preliminary materials are reviewed, additional biographical and complete dossiers may
be requested of applicants under consideration.
For additional information, please do not hesitate to contact Simon Ostrach at
[email protected] or Stephen Crandall at [email protected], who are current members of the
awards committee.
AAM Awards Committee
Simon Ostrach, Chair, Stephen Crandall, Tinsley Oden, Wolfgang Knauss, Romesh Batra
* Please note change in submission date from previous years.
V
NOMINATIONS FOR FELLOW OF
THE AMERICAN ACADEMY OF MECHANICS
NOTES:
• Persons nominated must be members of the Academy (Bylaws, III 1).
• Nominations must be made by two of the Fellows (Bylaws, III 2).
• Fellows shall be elected on the basis of their contributions to mechanics (Bylaws, III 1).
Name of the member nominated (please print)
Citation (please state in no more than fifteen words the basis of the nomination)
Nominated by (signatures of two fellows required)
Signature:
Printed Name:
Date:
Signature:
Printed Name:
Date:
Please mail this nomination form (no faxes please!) to:
Professor C. W. Bert
School of Aerospace & Mechanical Engineering
The University of Oklahoma
Norman, Ok 73019-1052, USA
so as to reach him on or before September 24, 2002. The nomination should include one good
copy of a two-page resume of the member nominated.
VI
American Academy of Mechanics
Founders Prize and Grant
Up to $10,000 For the Academic Year 2002-2003
(Deadline: July 1, 2002)
The American Academy of Mechanics is pleased to announce the
availability of a Founder’s Prize and Grant to be awarded in
September 2002 to a doctoral candidate in the field of Mechanics.
Funding
has
been
arranged
by
the
Robert
M.
and
Mary
Haythornthwaite Foundation through the good offices of Professor
Haythornthwaite, founder and first President of the Academy. The
aware will be made on the recommendation of an AAM committee. The
prize consists of a Certificate and $1,000 that will be presented
at the annual meeting of the Academy, usually held in November.
The Grant will be made to that same person in two installments,
$6,000 in September 2002 and up to $3,000 in January 2003, the
latter dependent on the size of the approved budget and receipt
by the AAM committee of an acceptable progress report. In order
to encourage contestants to think constructively about the impact
of new and pending developments, they will be asked to compose an
original essay of no more than a thousand words under the title
“Progress through Mechanics”. The winning essay will be
published in mechanics. The award is open to those who, as of
July 1, 2002, are registered as graduate students at a degree
granting institution within the Americas, have completed at least
one year of full-time graduate study at that institution, have
been assigned a thesis advisor at the institution and have had a
doctoral thesis topic emphasizing mechanics approved by the
institution following candidacy or equivalent procedures. There
are no restrictions with regard to citizenship, residency, race,
religion, or sex. Letters of support will be required of the
thesis advisor and in addition one from either a Member or a
Fellow of AAM. Contestants will be judged on the basis of the
essay, plans, references and academic history. The intent of the
Grant is to support the research of the student through an
approved combination of equipment purchases, information access,
travel, etc., but not routine living expenses or fees. Detailed
rules for the competition will be issued soon: to receive them,
express your interest to the committee by FAX to (215) 204-6936,
or by writing to:
AAM Founders Prize and Grant Committee
c/o Civil and Environmental Engineering Department
Temple University (084-53)
Philadelphia, PA 19122
VII
PACAM VIII
Eighth Pan American Congress of Applied Mechanics
January 5-9, 2004
Havana, Cuba
http://www.pacam8.mcgill.ca/
The Eighth Pan American Congress of Applied Mechanics (PACAM VIII), jointly sponsored by
the University of Havana, the Institute of Cybernetics, Mathematics, and Physics of Cuba, and
the American Academy of Mechanics, will be held January 5-9, 2004 at the Convention Center,
Havana, Cuba. The Honorary Chairman of the Organizing Committee is Prof. Alina Ruiz Jhones
of the University of Havana. The Co-Chairmen are Prof. Martin Ostoja-Starzewski of McGill
University and Prof. Reinaldo Rodríguez-Ramos of the University of Havana. The Chairman of
the Editorial Committee is Prof. Julián Bravo-Castillero of the University of Havana, and the
Chairman of the Local Arrangements Committee is Prof. Raúl Guinovart-Diaz of the University
of Havana, Cuba.
The aim of sponsors is to promote progress in the broad field of mechanics by (1) exposing
engineers and scientists, including graduate students, to new research findings, techniques, and
problems, and (2) providing opportunities for personal interactions between mechanicians of
North and South America, as well as other continents. It is the only conference sponsored by the
American Academy of Mechanics (AAM).
The Pan American Congresses of Applied Mechanics are held every two years early in January,
always in a Latin American venue, at a time when few other conferences are scheduled. The
previous Congresses were held in Rio de Janeiro, Brazil in 1989; Valparaiso, Chile in 1991; São
Paulo, Brazil in 1993; Buenos Aires, Argentina in 1995; San Juan, Puerto Rico in 1997, Rio de
Janeiro, Brazil in 1999 and Temuco, Chile in 2002. Participants come from the Americas as well
as Africa, Asia, Australia, and Europe.
Persons willing to organize special sessions in any area of mechanics are welcome to contact the
organizers listed below. All the future announcements will be made at the website listed above,
and through the AAM (http://www.AAMech.org/). Four-page papers for the conference
proceedings will be due June 30, 2003, at either address:
Latin American Co-Chairman
Prof. Reinaldo Rodríguez-Ramos
Facultad de Matemática y Computación
Universidad de la Habana
San Lazaro y L, Vedado, CP 10400
La Habana, Cuba
[email protected]
http://www.uh.cu
North American Co-Chairman
Prof. Martin Ostoja-Starzewski
Department of Mechanical Engineering
McGill University
817 Sherbrooke Street West
Montréal, PQ, Canada H3A 2K6
[email protected]
http://www.mcgill.ca
VIII
International Symposium on Dynamic Problems of Mechanics (X-DINAME)
Dynamics of the Brazilian Society of Mechanical Sciences
10-14 March, 2003
Hotel Recanto das Toninhas
Ubatuba, São Paulo
Call for Abstracts
Abstract Criteria:
Abstracts of scientific works are invited in all dynamic problems of mechanics. The work should
be original in scope, of outstanding quality and of permanent interest.
Abstracts are invited in the following topic areas:
• Structural and machine dynamics
• Control and optimization
• Noise and vibration
• Modal analysis
•
Any other correlated subject.
Information about the meeting:
The meeting is to take place on the week 10-14th of March, 2003 at Hotel Recanto das Toninhas
(http://www.toninhas.com.br), Ubatuba, São Paulo. Ubatuba is located somewhere in between
Rio and São Paulo, in one of the most attractive and exuberant coastal areas of Brazil, with a
consistent touristic structure of hotels and restaurants. It is adjacent to the preservation sanctuary
of the Atlantic Ridge Rain Forest and beautiful tropical beaches. The hotel, which is a resort by
the sea, provides the right kind of welcoming atmosphere and international standards service
which is required for the immersion activities of DINAME. Since the hotel has a limited number
of apartments early booking is encouraged.
Key Deadlines:
April 30, 2002: Last day for submission of abstracts for preliminary evaluation of contributions.
May 24, 2002: Notification of selected abstracts and invitation for submission of full texts.
July 31, 2002: Last day for receiving full texts.
August 30, 2002: Notification of accepted papers and/or required modifications of the text.
September 30, 2002: Last day for receiving modified texts.
January 15, 2003: Last day for confirming early booking with the hotel.
A home page for the conference is to become available soon. Any additional information can be
obtained by writing to the following address: [email protected]
IX
IUTAM Symposium
On
Integrated Modeling of Fully Coupled Fluid-Structure
Interactions Using Analysis, Computations, and Experiments
1 June-6 June 2003
New Brunswick, New Jersey USA
http://cronos.rutgers.edu/~mechaero/iutam
Chairs:
• Haym Benaroya and Timothy Wei, Rutgers University, New Jersey
[email protected] and [email protected]
Scientific Committee
• Peter Bearman, Imperial College of Science, Technology and Medicine, UK
• Earl Dowell, Duke University, North Carolina
• Helmut Eckelmann, Georg-August-Universität, Germany
• Peter Monkewitz, IMHEF-EPFL, Switzerland
• Michael Païdoussis, McGill University, Canada
• John Sheridan, Monash University, Australia
•
H.K. Moffatt, Isaac Newton Institute for Mathematical Sciences, UK
This Symposium will provide a forum for the latest thinking in analytical,
computational and experimental modeling of structures interacting with fluid
environments. The specific objective is to provide a structured format in
which meaningful and lasting dialogues can be facilitated between leading
researchers in the different component disciplines. It is intended that,
through these dialogues, multidisciplinary linkages will be established
leading to integrated approaches to modeling the complex, nonlinear
interactions between fluids and structures. Examples of classes of
interactions that may be addressed in this Symposium include ocean
structures, fluid conveying structures, and aerospace structures. The energy
transfer processes are inherently nonlinear in all aspects of the behavior.
The important class of vortex-induced oscillations has regions of lock-in,
where the structural natural frequencies rather than the fluid velocity
govern the shedding, and there exists hysteretic behavior. The real fluidstructure system is one of complex exchanges of forces and energies,
resulting in highly nonlinear behaviors. The ability to model, solve and
test fully coupled fluid-structure systems portends a rich and profound
understanding. In fact, recent research efforts have indeed started to focus
on the development of fully coupled models. This Symposium is therefore a
response to these new and exciting developments in the field. By bringing
together a critical mass of key researchers in each discipline, and
organizing the program to focus on multidisciplinary problem solving, this
process of developing fully coupled fluid-structure interaction research
programs can be reinforced and enhanced. We look forward to receiving
abstracts for review, presentation, and eventual full publication, of topics
that fall within the broad framework defined above.
DEADLINES
Submission of Abstracts: 1 February 2003
Notification of Acceptance: 15 March 2003
Hotel & Symposium Registration: 1 May 2003
Symposium: Sunday 1 June – Friday 6 June 2003
Final Manuscripts Due: Friday 13 June 2003 (FIRM)
X
FOURTH INTERNATIONAL SYMPOSIUM
ON VIBRATIONS OF CONTINUOUS SYSTEMS
The Fourth International Symposium on Vibrations of Continuous Systems will take place in
Keswick, England, July 7-11, 2003. The primary goal of this Symposium is to bring together outstanding
experts in the field of vibrations of continuous systems from all over the world, to discuss technical topics
in a very informal atmosphere. As before, participation will be by invitation only, and will be limited to
maximum numbers of 50 participants and 40 presentations.
The Symposium is devoted to the vibrations of continuous systems (e.g. strings, rods, straight and
curved beams, membranes, plates, shells, and three-dimensional bodies). Examples of topics to be
considered include: free and forced vibration, linear and nonlinear vibration, undamped and damped
vibration, fluid-structure interaction, and structural elements of composite material.
The Symposium location, Keswick, is in the heart of the Lake District of northwestern England,
famous for its beautiful lakes and hills. Typical days at the Symposium will consist of morning hikes or
bus excursions, presentation sessions in the afternoons, and social gathering times in the evenings. The
outings and social gatherings have proved to be excellent ways of generating relaxed and informal
technical discussions and friendships which have been of great value to ongoing research.
Individuals who are interested in taking part in this Symposium should write to:
Professor Arthur W. Leissa
General Chairman, ISVCS IV
Dept. of Mechanical Engineering
206 West 18th Ave.
Ohio State University
Columbus, Ohio 43210
USA
Letters should be accompanied by a one-page summary of the writer’s research accomplishments (include
a list of published books, papers, reports, etc.) in the theme of this Symposium.
AAM Annual Business Meeting
The Annual Business Meeting of the American Academy of Mechanics will be held on Thursday, June
27, 2002, in conjunction with the 14th USNCTAM Meeting (June 23-28, 2002) at the Virginia Polytechnic
Institute and State University at Blacksburg. The conference banquet will be held in the evening from
7:00 p.m. to 10:00 p.m. Plan now to participate in the AAM business meeting.
The Board of Directors will meet 11:30 a.m. to 1:30 p.m. for a working luncheon. The Secretary will
issue an agenda within thirty days prior to the Board Meeting.
The Fellows Meeting will convene from 1:30 p.m. to 2:30 p.m. At this time, the President-Elect presiding
and in accordance with Bylaw Article III.3: “The Fellows shall elect one of their number as Secretary to
the Fellows.” The term of office shall be from three to five years, to be specified.
The General Members Meeting will be held from 2:30 p.m. to 3:30 p.m.
XI
CALL FOR NOMINATIONS
FOR DIRECTOR OF REGION IB,
CENTRAL AND WESTERN USA
Nominations are called for Director of Region IB, Central and Western USA, for a three-year term of
service commencing in June 2003. The nominee must be an active Member of the Academy registered in
that region; and nominations shall be accepted only from active Members resident in that region. Valid
nominations must bear the signatures of five (5) Members of the Academy who are residents of the region
and are Members in good standing. Nominations shall include a letter from the nominee accepting the
nomination. The deadline for submissions is September 30, 2002. Early nominations are strongly
encouraged.
Please submit all nominations to
Professor Dean Mook, Secretary
American Academy of Mechanics
Department of Engineering Science and Mechanics
Virginia Polytechnic and State University
Blacksburg, VA 24061-0219
CALL FOR NOMINATIONS
FOR DIRECTOR OF REGION III,
CENTRAL AND SOUTH AMERICA
Nominations are called for Director of Region III, Central and South America, for a three-year term of
service commencing in June 2003. The nominee must be an active Member of the Academy registered in
that region; and nominations shall be accepted only from active Members resident in that region. Valid
nominations must bear the signatures of five (5) Members of the Academy who are residents of the region
and are Members in good standing. Nominations shall include a letter from the nominee accepting the
nomination. The deadline for submissions is September 30, 2002. Early nominations are strongly
encouraged.
Please submit all nominations to
Professor Dean Mook, Secretary
American Academy of Mechanics
Department of Engineering Science and Mechanics
Virginia Polytechnic and State University
Blacksburg, VA 24061-0219
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SELECTIONS OF THE EDITOR
The Future of the Microprocessor Business
Reprinted with permission from Spectrum
Vol. 39, No.4, April 2002
By Michael J. Bass and Clayton M. Christensen
In a century in which technology left few aspects of life unchanged in some countries, the microprocessor
may have been the most transformative of all. In three decades it has worked itself into our lives with a
scope and depth that would have been impossible to imagine during its early development.
If you live in a developed country, chances are good that your household can boast of more than a
hundred microprocessors scattered throughout its vehicles, appliances, entertainment systems, cameras,
wireless devices, personal digital assistants, and toys. Your car alone probably has at least 40 or 50
microprocessors. And it is a good bet that your livelihood, and perhaps your leisure pursuits, require you
to frequently use a PC, a product that owes as much to the microprocessor as the automobile owes to the
internal combustion engine.
Throughout most of its history, the microprocessor business has followed a consistent pattern.
Companies such as Intel, Motorola, Advanced Micro Devices, IBM, Sun Microsystems, and HewlettPackard spend billions of dollars each year and compete intensely to produce the most powerful
processors, which handle data in 32- or 64-bit increments. The astounding complexity and densities of
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transistors on these ICs—now surpassing 200 million transistors on a 1-cm die—confer great technical
prestige on these companies. The chips are used in PCs, workstations, and other systems that, for the
most part, have been lucrative, high-volume markets.
As with other ICs, microprocessors have for the past few decades been undergoing the exponential rise
in performance prophesied by Moore's Law. Named for Intel Corp.'s cofounder, Gordon E. Moore, it
describes how engineers every 18 months or so have managed to double the number of transistors in
cutting-edge ICs without correspondingly increasing the cost of the chips. For microprocessors, this
periodic doubling translates into a roughly 100 percent increase in performance, every year and a half, at
no additional cost. The situation has delighted consumers and product designers, and has been the main
reason why the microprocessor has been one of the greatest technologies of our time.
In coming years, however, this seemingly unshakable industry paradigm will change fundamentally. What
will happen is that the performance of middle- and lower-range microprocessors will increasingly be
sufficient for growing—and lucrative—categories of applications. Thus microprocessor makers that
concentrate single-mindedly on keeping up with Moore's Law will risk losing market share in these fastgrowing segments of their markets. In fact, we believe that some of these companies will be overtaken by
firms that have optimized their design and manufacturing processes around other capabilities, notably the
quick creation and delivery of customized chips to their customers.
The changes portend serious upheaval for microprocessor design, fabrication, and equipmentmanufacturing firms, which have been laser-locked on Moore's Law. Executives lose sleep over whether
they can keep on shrinking line widths and transistors and fabricating larger wafers. We don't blame
them, given their history. Nor do we see blissfully peaceful slumber in their near future: this is not another
article forecasting the imminent demise of Moore's Law.
On the contrary, we believe that the top IC fabricators will have little choice but to invest ever more
heavily so as to keep on the Moore trajectory, which we expect to go on for another 15 years, at least. We
don't see these investments as sufficient for future success, however.
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Will semiconductors hit a physical limit? They surely will, someday. But this is probably the right answer to
the wrong question. The more important question is: as technological progress surpasses what users can
use, how do the dynamics of competition begin to change?
Bottom to top
The stakes are high. The microprocessor market, which totals about US $40 billion a year, has several
main tiers. At the top are the most powerful chips, which are used in servers and workstations. Then
there's the PC market, dominated by Intel microprocessors. These relatively high-end chips were a major
component of a category that rang up US $23 billion in 2001, after peaking at $32 billion the year before,
according to the Semiconductor Industry Association (San Jose, Calif.), a trade group.
Microcontrollers were another important category, with sales totaling $10 billion in 2001. They are
generally less computationally powerful than high-end microprocessors, and exert real-time control over
other systems, such as automobile engines. Finally, digital signal-processing chips, a key component of
cell phones, DVD players, and other entertainment products, had sales of $4 billion last year.
With their exponentially increasing performance, microprocessors might seem unique and unlikely to
follow the broad evolutionary pattern that has played out in the past in most other technology-based
industries. After all, the Moore's Law phenomenon is unprecedented in industrial history. But strong
evidence shows that the same evolutionary pattern that occurred in mainframe computers, personal
computers, telecommunications, banking, hospitals, and steel production is indeed occurring in the
microprocessor business.
The pattern begins with a stage in which available products do not yet perform up to most customers'
needs. So, not surprisingly, companies compete by making better products. In other words, competition
during this stage is basically driven by performance. As engineers design each successive generation of
product, they strive to fit the pieces together in ever more efficient ways to wring the most performance
possible out of the technology available.
Typically, major subsystems need to be interdependently designed—and, as a result, a competitor needs
to make all the product's critical subsystems. During this phase, the competitive advantage of vertical
integration is substantial, so manufacturers do almost everything themselves. This is the way it was in the
earliest days of the PC industry, for example.
The next stage of an industry's development begins when the performance of its products has overshot
the needs of customers in the less-demanding tiers of the market. These customers won't pay premium
prices for more performance, of course, but will pay extra for a product that is extraordinarily reliable, or
one that has been customized to meet their specific needs—especially if they can get that ultra-reliable or
customized product quickly and conveniently. Ease of use is another feature that customers typically
reward with a premium.
To compete on the dimensions of customization, quick delivery, and convenience, product architectures
whose pieces are strongly technologically interdependent tend to give way to modular ones, in which the
interfaces among subsystems are standardized. This modularization lets designers and assemblers
respond quickly to changing customer requirements by mixing and matching components. It also lets
them upgrade certain subsystems without redesigning everything.
But perhaps the most important repercussion of modularization is that it usually spurs the establishment
of a cadre of focused, independent companies that thrive by making only one component or subsystem of
the product. Think Seagate Technology in hard-disk drives, or Delphi Delco in automotive electrical
systems.
One of us (Christensen) has studied how industries that are in transition between the two stages present
peril for established firms—and opportunity for upstarts. Large firms can easily become blind to shifts in
the types of performance that are valued. For an established company, with its well-defined competencies
and business models, the obvious opportunities for innovation are those that focus on unsatisfied
customers in the higher market tiers. After all, that is where the innovations that the company has
structured itself to deliver are still being rewarded by premium prices.
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Inevitably, though, this high-tier, performance-hungry group of customers shrinks as performance gets
better and better. At the same time, in lower market tiers there is a huge increase in customers who are
willing to back off from the leading edge of performance in exchange for high reliability, customization,
ease of use, or some combination of all three.
Too much of a good thing?
This is precisely the juncture at which the microprocessor market has now arrived. Price and
performance, fueled by the industry's collective preoccupation with Moore's Law, are still the metrics
valued in essentially all tiers of the market today. Even so, there are signs that a seismic shift is occurring.
The initial, performance-dominated phase is giving way to a new era in which other factors, such as
customization, matter more.
Perhaps the best evidence that this shift is under way is the fact that leading-edge microprocessors now
deliver more performance than most users need. True, emerging applications like three-dimensional
games, the editing of digital-video files, and speech-to-text tax the fastest available microprocessors.
However, few people who regularly run such applications do so on a single-microprocessor PC. And that
fact is unlikely to change. In the future, as now, many of these taxing applications will run on specialpurpose or separate processors.
Hundreds of Athlon microprocessors, from Advanced Micro Devices, are fabricated on 200-mm wafers at a new plant in Dresden,
Germany [above]. Though designed for PCs, the 1-GHz chips perform beyond the levels most PC users need. MATTHIAS
RIETSCHE/AP PHOTO
In any case, the users who run these applications regularly are few compared to the masses who use
their PCs mainly for word processing, scheduling, e-mail, and Internet access. For this majority, high-end
microprocessors—Intel's Itanium and Pentium-4, and Advanced Micro Device's Athlon—are clearly
overkill. Running common benchmark programs, these chips can perform more than one billion floatingpoint operations per second (flops), and in some cases, more than 2 gigaflops. Yet, Microsoft's Windows
XP, the most recent version of the ubiquitous operating system, runs fine on a Pentium III
microprocessor, which is roughly half as fast as the Pentium-4.
What will the microprocessor business be like after this shift? Consider how the PC business grew from a
cottage industry into a global colossus over the past 25 years.
In the early days, the 1970s, vertically integrated companies such as Apple Computer, Tandy, Texas
Instruments, Commodore, and Kaypro built their computers around proprietary architectures and
generally wrote their own software. Then, in 1981, IBM shook up the industry with its original PC, which
had a modular architecture and subsystems built by such suppliers as Intel, Microsoft, and Seagate.
Early on, Apple's products were by consensus the best-performing and most reliable in the industry. But
in time, as microprocessors, software, and other key components improved, garden-variety PCs became
good enough for mainstream applications like word processing and spreadsheets. Competitive advantage
shifted to the nonintegrated companies whose products made use of IBM's modular architecture. These
were the clone makers—Compaq, Packard Bell, Toshiba, AT&T, and countless others. Not long after
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that, dependability became the central axis of competition, and a few firms with reputations for reliability—
IBM, Compaq, and Hewlett-Packard—managed to command price premiums.
By the early to mid-1990s, functionality and reliability had become more than good enough from just
about everyone, and the way that computer makers needed to compete shifted again. This change set
the stage for Dell Computer Corp. (Round Rock, Texas) to rocket from the lowest tiers of the market to
industry dominance. Dell let consumers in their homes or offices specify a set of features and functions
for their computer to meet their particular needs. Dell then delivered that computer to their door in a few
days. In effect, by coming up with a business model that emphasized customization, speed of delivery,
and convenience, Dell pushed the industry into its next stage of development.
Although our example is PCs, other technology-based industries have evolved similarly, from automobiles
to mainframes. In every case, the primary dimension of competition migrated from an initial focus on
performance to reliability, convenience, and customization. When performance began exceeding what
customers in a tier of the market could use, competition redefined the types of improvement for which
those customers would pay extra. Further, the types of features that let suppliers demand premium prices
shifted predictably from performance to reliability, convenience, and so on. As this happened, moreover,
competitive advantage moved from companies that were highly integrated to ones that were not.
Why don't microprocessor makers simply start producing lower-performance chips? A few years ago, Intel
Corp. (Santa Clara, Calif.) began doing just that with its Celeron microprocessor. The problem is that
Celeron is a one-size-fits-all proposition. Its architecture isn't more modular than that of the Pentium
products it is displacing, and it cannot be customized nearly as much as emerging alternatives.
Interestingly, while the latest microprocessors offer higher processing rates than most users need,
semiconductor fabrication facilities now offer circuit design teams more transistors than they need[see
figure]. Put another way, the rate at which engineers are capable of using transistors in new chip designs
lags behind the rate at which manufacturing processes are making transistors available for use.
This so-called design gap has been widening for some time. In fact, the National Technology Roadmap
for Semiconductors noted it five years ago, observing that while the number of transistors that could be
put on a die was increasing at a rate of about 60 percent a year, the number of transistors that circuit
designers could design into new interdependent circuits was going up at only 20 percent a year.
Microprocessors hundreds of times as powerful as today's should emerge from chip-making equipment using extreme ultraviolet
radiation. Sandia National Laboratories unveiled such equipment a year ago [above]. PAUL SAKUMA/AP PHOTO
The fact that microprocessor designers are now "wasting" transistors is one indication that the industry is
about to re-enact what happened in other technology-based industries, namely, the rise of customization.
Keep in mind that in order to develop a modular product architecture with standardized interfaces among
subsystems, it is necessary to waste some of the functionality that is theoretically possible. Modular
designs by definition force performance compromises and a backing away from the bleeding edge.
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Core customization
A form of customization has already taken hold in the lower tiers of the microprocessor industry. Systemon-a-chip (SoC) products are modular designs constructed from reusable intellectual property (IP) blocks
that perform specific functions [see "Crossroads for Mixed-Signal Chips," IEEE Spectrum, March 2002,
pp. 38-43]. IP blocks vary in size and complexity, ranging from simple functions such as an RS-232 serial
port interface or a DRAM memory controller, to a complex subsystem, such as an entire 32- or 64-bit
microprocessor. These IP blocks can be used within multiple designs within a company, or used in
designs at different firms.
In the lower market tiers, several firms are bundling IP blocks into both soft cores (software-like
descriptions of the IP blocks that can be synthesized into hardware designs) and hard cores, that is, preverified hardware designs. Such cores range from hundreds of thousands to a few million transistors, and
their availability in the marketplace enables firms to focus less on new design and more on system
integration. They can select and integrate microprocessor and other types of cores into SoC designs that
are then manufactured as special-purpose components for a specific product.
Recently, a few companies have been pushing this trend toward component selection and integration
even further, into microprocessor cores themselves. Using special design tools, engineers can specify
such a microprocessor, and in some cases completely design one, in weeks rather than months.
The Impact of Disruptive Technology
As the performance of conventional microprocessors improves [red line], they first meet and then exceed the requirements of most
computing applications [dotted lines]. Initially, performance is key [blue area]. But eventually, other factors—reliability, time-tomarket, convenience, and customization—become more important to the customer [green area]. And when a disruptive technology
[orange line], such as customizable processor cores, is introduced, it inevitably takes over market share from performance leaders.
Leading companies in this so-called customizable core movement include Tensilica, ARC Cores, HewlettPackard, and STMicroelectronics. They have a similar philosophy, but target different markets and
application needs. The Tensilica Xtensa processor, for instance, offers customization within the
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framework of a simple microprocessor core. Customers can specify their own instruction set extension by
accessing a Web site and using a high-level language, such as Verilog.
ARC Cores' ARCtangent family targets the digital signal processor markets. Like Tensilica, it allows users
to customize both processor features (bus widths, cache sizes, and so on) and instructions. HewlettPackard's HP/ST Lx family is aimed at scalable multimedia acceleration using Very Long Instruction Word
(VLIW) techniques. It lets customers choose the amount of instruction-level parallelism—in other words,
how many functional units to include, and how many operations can be performed in parallel.
Intel's dilemma
So what will happen in the microprocessor market as a whole? It will be a repeat of what has already
happened in other technical industries. The trends of customization and speed-to-market will continue to
take hold in the lower tiers—in digital signal processing (DSP) and in processors that are embedded
within such products as MP3 players, digital cameras, and set-top boxes. Increasingly, sales of standalone digital signal-processing and embedded chips will give way to SoCs that incorporate DSP or other
functions.
Gradually, over a period of years, the trend will creep upward into higher tiers of the market, including
PCs [see graph]. In fact, companies such as SuperH, MIPS Technologies, and ARM already produce
reduced-instruction-set microprocessor cores that can be combined on a single die with other functional
units, and that are easily powerful enough to serve as a PC's central processing unit.
Engineers can specify a microprocessor and in some cases completely design one in weeks,
rather than months
For high-end companies such as Intel, the dilemma will be that their best and most profitable customers
will continue to need exactly the sort of general-purpose, leading-edge processors that Intel is so good at
designing and delivering. Nevertheless, broad trends in electronics suggest that growth will increasingly
stem from applications in the lower tiers.
For example, sales of PCs, the largest market for high-end microprocessors, declined in 2001 for the first
time since 1985, according to market research firm Gartner Dataquest (Stamford, Conn.). Meanwhile,
although the market for DSPs shrank even more than the rest of the microprocessor category last year,
on the whole they have been one of the fastest-growing segments of that category. The growth has been
fueled by such up-and-coming sectors as wireless communications, handhelds, and game, music, video,
and other entertainment systems.
Custom Chips and Future Fabs
As custom-configured chips carve out a larger portion of the microprocessor market, major changes are in store for the way chip
fabrication facilities operate. To understand why, consider the underlying trends. One is the ever-increasing abundance of
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transistors on a chip, which portends a day when the number of chips per product will approach one. Also every chip will, to some
degree, be custom-tailored to its application, and product life cycles will be short. Put those trends together and the inescapable
conclusion is that, in the foreseeable future, chips will have to be made in a few days, not weeks, as they are now.
To achieve that kind of speed, chip fab plants must operate differently, starting with the way wafers flow through them. The dies are
fabricated in batches on round semiconductor wafers about the size of a dinner plate [photo].
In today's fabs, those wafers are also produced in batches. Therein lies the problem: as these groups of wafers move from station to
station in the fab plant, they have to wait until an entire batch is complete before going on to the next station. At any given time,
large amounts of valuable product are simply sitting around the plant.
In the future, wafers will need to move rapidly, one by one, through these plants. The difficulty will be finding a way to implement this
single-wafer processing in a variety of fabs, all of which have their own proprietary architecture. To our knowledge, no firm as yet
has figured out how to do this, though Taiwan Semiconductor Manufacturing Co. (Hsinchu) and United Microelectronics Corp.
(Taipei) have made significant progress in this direction.
Single-wafer processing will also probably compromise the economic viability of investments in 300-mm wafer-processing
equipment. The reason is that, in the past, when a factory converted to a low-inventory process flow (such as single-wafer
processing), the effective capacity of that plant typically doubled.
What this means for fab plants is that it makes more economic sense to convert a 200-mm-wafer fab plant to single-wafer
processing, rather than build a 300-mm-wafer fab plant. The 200-mm, single-wafer-processing fab plant could be expected to
process twice the number of wafers per month and therefore as many die as the 300-mm fab—and to do so at much lower levels of
cost and complexity. —M.J.B. & C.M.C.
Implications, implications
If the microprocessor market does become dominated by multitudes of targeted chips produced in
relatively small numbers, several intriguing ramifications could develop. First, for chip-makers, time to
market will matter much more [see "Custom Chips and Future Fabs"]. Second, as firms target smaller,
more specific markets, they will differentiate their products more by discovering specific needs that
general-purpose products do not address.
This discovery process works better when products are introduced faster and more frequently, in
response to feedback from customers. Tensilica, for one, now boasts that new microprocessor cores
used within a system-on-a-chip design can be created and their performance tested through simulation in
two weeks. The manufacturing latency of most chip fabrication facilities, on the other hand, remains as
high as 10 weeks.
With product life cycles approaching a year or less, some microprocessors currently spend a good part of
their lives being manufactured. In the future this situation will be competitively intolerable.
In coming years, success in the microprocessor business will increasingly demand that companies:
•
Adeptly use modular designs that reuse and recombine silicon intellectual property.
•
Include multiple circuit types and possibly process technologies on a single die, creating customtailored systems-on-a-chip.
•
Shrink the design cycle for microprocessors and systems-on-a-chip and dramatically reduce
manufacturing latency times (time spent in the plant).
•
Tolerate, both technically and economically, a manufacturing mix composed of a multitude of lowvolume runs of narrowly targeted products with short market windows.
The evolution toward this future will not be driven by or grounded in the choices of managers in today's
industry-leading companies. Competition in the relevant tiers of the market will force these new
trajectories of improvement to become critical. The only question is which companies will have developed
the capabilities and organizational structures required to thrive in these markets.
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The Opportunity and Threat of Disruptive Technologies
Reprinted with permission from MRS Bulletin
Vol. 27, No.4, pp. 278-282, April 2002
By Clayton M. Christensen
The following article is an edited transcript of the plenary presentation given by Clayton M. Christensen
(Harvard Business School) at the 2001 Materials Research Society Fall Meeting on November 26 in
Boston.
Introduction
I am honored to be with you today. I will give context for where the puzzles developed that have
led to the research that I summarized in the book The Innovator’s Dilemma. Companies that at
one point were very successful and widely admired, fell from their leadership position within 5
to 10 years. This was very poignant for minicomputer companies, for example, which collapsed
after their peak in the world economy during the 1970s and 1980s. While the companies were
thriving, the business press attributed their successes to the abilities of their management teams.
However, when these companies began to quickly unravel around 1988, the business press
attributed their failures to the ineptitude of the very same management teams that had been in
place during the years of success. I wondered how good managers could get that bad that fast. I
was also suspicious because the minicomputer companies fell in unison. It was not just Digital,
but also Data General, Prime, Wang, and Nixdorf. While the companies could have colluded on
price, they would never have colluded to collapse together. Something more fundamental had to
be happening. Oddly, I found that the reason these companies failed, not just in the computer
industry, but over and over again in a variety of industries, is that they were well man-aged.
The Disruptive Technology Model
Certain paradigms of good management that we teach in business schools sow the seeds of a
company’s eventual failure. Figure 1 presents a model that consists of three elements. The
performance of a product or service is plotted over time. The first element of the model,
represented by the dotted line, shows a trajectory of improvement that customers can absorb or
utilize over time. This line represents the median in every market. At the high end of every
market, customers are very demanding and will never be satisfied with the best products
available. At the low end are customers who can be satisfied by very little.
The steeply sloping lines of the figure represent a distinctly different trajectory of improvement
in the market. They rep-resent the improvement that innovators make available as, generation
after generation, they introduce new and improved products. This trajectory of technological
progress almost invariably outstrips the ability of customers to utilize those improvements;
companies can almost always innovate faster than people’s lives can change to fully utilize those
innovations. In pursuing more profitable customers who will pay higher prices for better
products in more demanding tiers of the market, companies are prone to over-shoot what the
original set of customers is able to utilize at a later point in time. For example, in the mid-1980s
when we were first learning to do word processing on those early personal computers, it was not
uncommon for us to have to stop our fingers and wait for the Intel 8088 processor to catch up
with us. But as Intel has pursued more profitable customers, to whom it could sell better products
for higher margins, it has way-overshot what customers in the mainstream of the business
computing market are able to utilize. What this also means is that technology that is initially not
good enough to be embraced by customers in the mainstream of the market can improve at such
a rapid rate that it later intersects with the needs of mainstream customers.
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The third piece of the model relates to “disruptive technology,” which refers to technology that
initially underperforms the incumbent technology, but typically offers more flexibility,
convenience, or a lower price. A disruptive technology can serve to create new markets, but it
can also upset the equilibrium of companies with good reputations and good products.
Disruption in Action
Computer Industry: From Disk Drives to Intel
I initiated my study of what was driving the failure of some groups of firms with the disk drive
industry. In five of six product generations in the industry, a new company would enter and rise
to the top only to be toppled by another company that entered and rose to the top. I wanted to
develop a model that would explain this phenomenon, which I could then apply to other
industries. The disk drive industry served as the “fruit fly” in which it was possible to study
many “generations” quickly.
Through this process of the disk drive study, we built a database of every model of every disk
drive introduced in the industry’s history. For each of the products, we obtained data on each of
the components that was used in the drive. This allowed us to locate the point in the industry’s
history at which each new technology was first used. In this process, we identified 116 distinctly
different new technologies. Of the 116, 111 sustained the trajectory of performance improvement
in the market, as it existed at the time. In other words, the purpose of the technology was to make
a good product better. Of these 111 sustaining technologies, a good number were the simple,
year-to-year engineering advancements expected of good companies. Additionally, a remarkable number were truly breakthrough innovations that made good products much better, as
depicted in Figure 1. What was interesting is that it did not matter technologically how difficult
the innovation was. In all 111 of these cases, 100% of the time, the companies that led the
industry in developing and adopting the new technology had been the leaders of the old
technology. As long as the innovation enabled the company to make a better product that they
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could sell for higher margins to their best customers, it was on management’s radar screen and it
received the necessary resources to get it done. Only five technologies disrupted this trajectory of
improvement, which means they brought to the market a product that was not as good as what
historically had been available. Oddly, this type of technology always killed the industry leader;
in none of these cases did the company that had been the leader in the prior generation survive
into the next generation. Even more remarkable, these were relatively simple technologies.
Let us take this phenomenon to the computer world. When we consider the sequence of
minicomputers that Digital introduced into its markets through the 1970s and 1980s, it had a
perfect record in developing the technologies—whether incremental or radical—that sustained
the trajectory of improvement in many computers. The early personal computers that emerged in
the late 1970s and early 1980s—such as the Apple II, marketed to children as a toy—were a
disruptive technology. Digital received no signal from the market that the personal computer
mattered because none of its customers could use personal computers. They were not good
enough. Yet, because the trajectory of technological progress outstrips the ability of customers to
use it, what was at one point a toy improved at such a rapid rate that it intersected with the
customers’ needs of many computer users at a later point in time. A whole population of
minicomputer companies was knocked out of the market together as a result of listening to their
customers.
When I was consulting recently with the senior management at Intel, the chair, Andy Grove,
puzzled over my description of “disruptive technology,” and recast it. He said the concept could
be more accurately characterized as trivial technology that disrupts the business model of the
leaders, which is what makes it difficult to handle. Grove said that Digital did not have a
technology problem, but rather a problem with its business model. For example, a minicomputer
is fairly expensive and complex, and it has to be sold directly to the customer. Digital had to
make gross margins of about 45% just to be acceptably profitable in the market. The senior
management faced proposals to invest in two types of products. Some entailed developing better
computers than Digital had ever made before that it could sell for $200,000 and 60% gross
margins by penetrating the market where customers had historically only been able to use
mainframes. Other proposals entailed investing in personal computers that could be sold for
$2,000 and, in the very best of years, promised gross margins of only 40% that were headed to
20% rapidly. Grove concluded that the choice management had to make was whether to invest in
better products that would serve the best customers, which would improve the company’s profit
margins, or invest in worse products that their customers could not use and that would erode the
company’s profit margin.
This is the innovator’s dilemma. For 111 of the 116 cases in the disk drive study, these
paradigms of good management— listening to your best customers and focusing investments on
those innovations that promise the highest profit margins—provided good guidance for the
innovators. However, in the five cases in which the disruptive technology came in, those same
paradigms of good management paralyzed the leading companies and made it impossible for
them to respond.
From Steel Mini-Mills to Sony
Let us look now at a very different industry, which is the steel industry. The question is how did
the steel mini-mills in North America grow to account for half of steel production? Most of the
world’s steel is made in large integrated mills that require billions of dollars to build. Mini-mills,
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in contrast, melt scrap in electric-arc furnaces and can make steel of any given quality for a 20%lower cost than integrated mills.
While it seems that every leading steel company worldwide would take on mini-mill technology
because the technology is straightforward and the chance to reduce the costs of making a
commodity like steel by 20% is a sure path to profit. Right? But not a single integrated steel
company in North America or Europe has yet successfully invested in a mini-mill. Only recently,
a few companies in Japan have acquired already successful mini-mills. When mini-mills became
technologically viable in the mid-1960s, the quality they could produce was very low. Only the
concrete reinforcement-bar market accepted their product because rebar had pretty loose
specifications. As the mini-mills attacked the competitive rebar tier of the market, the integrated
mills happily dropped out of that tier because their gross margins in that market segment were
only about 7%. As the mini-mills expanded their capacity, the integrated mills shut the lines
down or reconfigured them to make more profitable products. By about 1975, the mini-mills had
driven the integrated mills out of the rebar market. The mini-mills, with a 20% cost advantage,
made lots of money making rebar in competition with the high-cost integrated mills. But when
they finally succeeded in driving the last integrated mill out of the rebar market in about 1975,
the price of rebar collapsed by 20%—because you now had low-cost mini-mills slugging it out
with low-cost mini-mills in a commodity market. How could they begin making money again?
They had no option but to turn to products that were larger and of higher quality, which means
they attacked the next tier up of the market: angle iron and thicker bar and rod. The mini-mills
little by little figured out how to make better products. As they hit the next tier of the market, the
integrated mills were happy to get out of it, too, because the 12% margins were still relatively
low. As the mini-mills expanded capacity, the integrated mills shut the lines down and
reconfigured them to make better products, and while the mini-mills were competing against the
high-cost integrated players, the mini-mills once again made a lot of money—until 1984, when
they succeeded in driving the last high-cost integrated player out of the angle-iron market. The
price of angle iron then dropped by 20%.
The mini-mills then moved up into structural beams. The margin that the integrated mills were
making in structural beams was about 18%, and the market was three times larger than those the
mini-mills had already conquered. In the early 1980s, beams could not be rolled in a mini-mill
format to meet specifications. The mini-mills, however, figured out how to roll high-end
structural bar—like 12-, 16-, and 24-inch I-beams and H-beams. By 1992, they had driven U.S.
Steel out of the structural-beam market. By 1996, Bethlehem Steel had also been driven out of
that market.
Integrated steel companies apparently practiced good management. Every time they lopped off
the low end of their product line, their reported gross-profit margins improved. Also, every time
the mini-mills added the very same products to the high end of their product lines, their reported
gross-profit lines improved. As a perfect symmetry of motivation, the high-end players were
motivated to leave the very markets that the low-end players were motivated to enter.
Other companies that recently experienced this kind of phenomenon include Sony, which came
into the low end of the market with low-quality transistor pocket radios in the mid-1960s. Sony
then became the highest-quality electronics maker worldwide. Seiko started with the inferior
plastic digital watch and then became the highest-quality watchmaker worldwide. In the
photocopier industry, Canon competed against the huge machines by Xerox with a low-end,
limited-feature, tabletop photocopier that filled a niche for small companies. Xerox’s customers
XXIII
could not use the little tabletop machines, but in a different application, the inferior machine
moved up-market, and so customers consumed infinitely more photo-copying as a result of that
industry having been disrupted.
Interdependent and Modular Architectures
In the early 1980s, IBM had better operating- system technology than did Microsoft and better
microprocessor technology than did Intel. Yet, IBM chose to outsource the two technologies to
those respective companies and in the process put into business the two companies that
subsequently dominated the computer industry. IBM designed and assembled computers, where
subsequently no money was made. At the time IBM made those decisions, it was generally
regarded as managerially astute. This experience brings up the question as to when to work inhouse and when to outsource.
A review of the history of most industries reveals that during the early period when the
performance of the product or service is not good enough for what customers in the mainstream
need, the architecture of the product tends to be proprietary and interdependent in character.
When the product is not good enough, competition is dictated through the development of better
products. A proprietary architecture in an interdependent architecture can come closest to the
frontier of what is technologically possible.
For example, in the early years of the mainframe computer industry, an independent supplier of
operating systems, core memory, or logic circuitry could not have existed because the design of
XXIV
each of those subsystems depended upon the design of each of the other subsystems. They had to
be interdependently architectured. An independent-contract manufacturer of mainframe
computers could not exist because the way mainframe computers were made depended upon the
way that they were designed, and the way that they were designed depended upon the way they
were going to be made.
Integrated companies initially tend to dominate their industries, such as IBM and Digital,
General Motors and Ford, Alcoa and U.S. Steel, and so on. In the most demanding tiers of these
markets, the architectures are still proprietary and interdependent.
Once the technology is more than good enough, how do companies compete for the business of
customers in the now-overserved tiers of the market? The answer is that they must compete
differently. They must compete in speed-to-market, in the ability to respond quickly to changes
in customers’ needs, and in the ability to customize the features and functions of products to the
needs of smaller and smaller niches of the market. To be fast, flexible, and responsive, the
architecture of the product has to evolve from an interdependent to a modular architecture—
ultimately one that is built around industry standards. When that happens, the industry tends to
disintegrate as specialized companies provide one piece of value added. The population of
specialized companies then tends to replace what were the dominant integrated companies in an
earlier era. In fact, the dominant integrated companies have to disintegrate in order to compete
effectively (see Figure 2).
In an interdependent architecture, the companies that make the money tend to be the ones that do
the design and assembly of the product that is not good enough, that is, the end-use product.
Companies that were the suppliers tended to live a miserable profit-free existence year after year.
So, for example, IBM, with 70% market share, made 95% of the industry’s profit. The
companies that supplied IBM were wrung out every quarter. General Motors had a 55% market
share; it made 80% of the industry’s profit. A supplier to General Motors made no money. In a
modular architecture, the company that makes the money tends to flip; those that design and
assemble the products that the customers use tend to get knocked out and the ones that make
money are the ones who supply the subsystems that are not yet good enough. To illustrate, if an
engineer at Compaq receives instructions to design a better computer than Dell, the engineer
could put in a faster microprocessor, a higher-capacity disk drive, or more dynamic randomaccess memory. However, anything the engineer does, the competitor can instantly copy. So the
ability to make money flips back to Intel, who provides the performance-generating sub-system
that the assembler has to use in order to keep it at their leading edge.
I recently published an article in Harvard Business Review called “Skate to Where the Money
Will Be.” The title refers to what made Wayne Gretzky a great hockey player: He skated not to
where the puck was, but to where it would be. It suggests that the place in the value-added chain
where the money is made at one point is not likely where it will be made in the future. This is
happening now in the car industry. Automobiles have become more than good enough for what
most consumers need. The industry used to take six years to design and deliver a new car. Now
the design cycle has converged on two years, and customers can order a car custom-assembled to
their specifications, deliverable in five days. Car companies accomplish this by shifting the
architecture of these cars from an interdependent to a modular architecture. They still pro-cure
subsystems from tier 1 suppliers. Inside the subsystems, just like an Intel chip set, the
architecture becomes more proprietary and interdependent even while the external interfaces of
these sub-systems become more standardized. True to form, the integrated car companies are
XXV
having to disintegrate to keep pace with the accelerating cycles. However, car companies like
GM sold off the pieces of their business where the money was subsequently likely to be made, as
did IBM. In other words, GM and IBM skated to where the money used to be rather than to
where the money would be in the future.
Modularity in Action: Advanced Materials
In many ways, the purpose of advanced materials is to be a sustaining technology; that is, to
improve the functionality of products at the leading edge. When we started our company,
Ceramics Process Systems, in the early 1980s, we introduced components made of ceramics to
the automobile-engine world. One of the leading European car companies that was a major
investor in our company wanted us to start making silicon nitride piston pins because the
calculations revealed that if we could reduce the mass of a reciprocating component in the
engine, it would greatly improve its efficiency. With the specifications they gave us, we molded
the piston pins. When the piston pins were tested, however, the test engine vibrated
uncontrollably. It turned out that over the years, the car company had distributed mass elsewhere
in the engine to compensate for the reciprocating mass of the steel. There simply was not a plugcompatible modular opportunity for the advanced materials at the edge of performance.
Everything depended upon everything else. We succeeded because we finally found applications
where the technology was almost plug-compatible, which is far away from the leading edge.
How Disruptive Growth Begins
The way disruptive technology makes it to the obvious existing market is by finding simple
applications and then gradually improving. Figure 3 shows that the transistor was a disruptive
technology relative to the vacuum tube because it could not handle the power in the early 1950s
that would be required to be used in the market as it existed at the time. Every one of the
XXVI
vacuum-tube players saw the transistor coming. They all worked on the technology in their
laboratories, but framed it as a technological deficiency instead of an opportunity. In other
words, companies were challenged with ways of making transistors good enough to be used in
the vacuum-tube market. But transistors took root in a completely new market. The first
application was for a small hearing aid in 1953. This application valued the transistor for the
very attributes that made it useless in the mainstream market. In 1955, Sony introduced its
pocket transistor radio, which was such a low-quality product that it did not compete in the
mainstream market. It only appealed to low-end customers, such as teenagers, because it enabled
them to do something that had not been possible before—such as listen to Elvis Presley out of
earshot of their parents. Sony moved up into portable televisions in about 1959, where a huge
new market emerged. Other companies felt no pain because the market served different kinds of
customers and different kinds of applications than their mainstream ones. By about the mid1960s, solid-state electronic components became good enough for the mainstream market to use
and they replaced vacuum tubes. This is a typical pattern. A disruptive technology first takes root
away from the core of the mainstream market, where users value it despite its limitations.
In the last chapter of The Innovator’s Dilemma, I discuss whether the electric vehicle and
photovoltaics are disruptive technologies. In its concern over air pollution, California passed
legislation in the early 1990s mandating that every car company had to sell 2% of its unit volume
in California as zero-emission or electric vehicles by 1998, or it would be prohibited from selling
gas-powered cars. The car companies worldwide mounted huge efforts to develop battery
technology for electric vehicles. By about 1996, it was clear that they would not accomplish this
goal. As an example, customers told Chrysler that they wanted a car that went about 250 miles
between refueling stops and could accelerate from 0 to 60 miles per hour in about nine seconds.
To get its electric minivan to accelerate fast and cruise far, Chrysler loaded 1600 pounds of leadacid batteries in the back of it. The minivan, however, only cruised 80 miles and accelerated
from 0 to 60 mph in 19 seconds. One unfortunate side effect was that it took four times longer to
stop this minivan than the gas-powered one because of the balance in the back. It retailed for
$100,000. During consumer tests, Chrysler found no buyer. The government has since pushed
the target date to 2003.
In studying this issue, one of my students determined that the industry is coming up with the
right answers to the wrong questions. The right question is locating the market in which a
customer wants a car that does not cruise far or accelerate quickly, and is cheap. He suggested
that parents of teenagers and people in the retirement community would prefer this type of car.
He suggested that people in places like Bangkok would find a use for such a car since they
cannot travel quickly on the streets and would actually prefer the car to shut down as they waited
in traffic.
Another limitation to forcing electric vehicles into existing applications is that they do not fit
with existing infrastructures. If plugged into a 100-V outlet, they take an unacceptable eight
hours to recharge. Even if every filling station was outfitted with 480 V of service, the car would
take 20 minutes to refuel; consumers will not want to wait that long. On the other hand, if the
electric vehicle were a neighborhood vehicle, designed not to drive on a freeway, but for teenagers to cruise around town to high school and see their friends, or for retirement communities, it
would be convenient for the users to plug in the vehicle overnight. By targeting such a market,
the car companies avoid the infrastructural interdependencies that happen when they stretch to
use the new technology in the most demanding applications. Over and over again, though,
leading companies try to force the technology into demanding, obvious, and large applications.
XXVII
One of the most personally rewarding things about The Innovator’s Dilemma has been the
number of people who have told me that our theory has helped them frame a problem that they
are facing in their own lives. I hope that you too will be able to use our frameworks to better
understand some of the issues that your company may be confronting.
Recommended Reading
1. C.M. Christensen, The Innovator’s Dilemma: When New Technologies Cause Great
Firms to Fail (Harvard Business School Press, Boston, 1997).
2. C.M. Christensen, M. Raynor, and M. Verlinden, “Skate to Where the Money Will Be,”
Harvard Business Review (November 2001), p. 72.
3. C.M. Christensen, T. Craig, and S. Hart, “The Great Disruption,” Foreign Affairs 80 (2)
(March/April 2001), p. 80.
4. C.M. Christensen and M. Overdorf, “Meeting the Challenge of Disruptive Change,”
Harvard Business Review 78 (2) (March–April 2000), p. 66.
Clayton M. Christensen, the Robert and Jane Cizik Professor of Business Administration at the
Harvard Business School (HBS), is the author of The Innovator’s Dilemma: When New
Technologies Cause Great Firms to Fail, a book that won the Global Business Book Award for
the best business book published in 1997. In 1984, Christensen co-founded Ceramic Process
Systems, a developer of ceramic products, for which he served as chair and president.
Christensen holds a BA degree in economics from Brigham Young University and an MPhil
degree in economics from Oxford University, where he studied as a Rhodes Scholar. He received
his MBA degree from HBS in 1979, graduating as a George F. Baker Scholar, and was awarded
his DBA degree from HBS in 1992. Christensen was a White House Fellow, serving the
secretaries of transportation.
XXVIII
Sobre El Sentido Del Progreso En La Teoria De Estabilidad Elastica
Luis A. Godoy, Universidad Nacional de Cordoba, Argentina
RESUMEN
En este trabajo se propone un acercamiento epistemologico a la teoría de estabilidad elástica,
considerando el pasaje de la teoría clásica a la teoría de estabilidad poscritica inicial. Se
caracteriza la teoría clásica mediante el estado del arte presentado por Timoshenko en 1936, y la
crisis conceptual que surge alrededor de la incompatibilidad entre resultados teóricos y
experimentales para el cilindro con carga axial. Se revisan los estudios de la etapa de transición
(1934- 1968) que ofrecieron una variedad de explicaciones incompletas o inadecuadas. Se
presenta el surgimiento de la nueva teoría propuesta por Koiter en su tesis doctoral. A
continuación se consideran dos posturas epistemologías para interpretar el cambio de teoría: la
primera, debida a Kuhn, considera las teorías como paradigmas y el cambio como
revolucionario; mientras que la segunda, debida a Lakatos, considera la estructura de programas
de investigación. Finalmente se analizan las limitaciones y aciertos de cada una de esas visiones
a la luz del cambio en la teoría de estabilidad.
INTRODUCCION
A partir de la década del 60 varios filósofos de la ciencia han estudiado las teorías científicas
como estructuras y se han interesado en cómo se produce el cambio teórico en la ciencia. Entre
las posturas mas reconocidas se encuentra la de Thomas S. Kuhn (1922-1996), centrada en el
concepto de paradigma y de cambio revolucionario (Kuhn, 1962); la de Imre Lakatos (19221974) sobre programas de investigación científica (Lakatos, 1978), y la de Larry Laudan sobre
tradiciones y utilidad como forma de explicar el cambio (Laudan, 1977). Alrededor de esta
problemática se mueve la racionalidad o irracionalidad que tienen los científicos para aceptar un
cambio de teoría y cómo es la estructura del cambio que se produce entre una teoría y otra que le
sucede.
¿En qué medida esos modelos de cambio son adecuados para todas las disciplinas y todas las
épocas? Según Kuhn, se trata de patrones universales, aunque los casos que sirvieron de estudio
a Kuhn fueron tomados de la física y la astronomía en el pasaje de la Edad Media al
Renacimiento o en los siglos XVII y XVIII. Han habido fuertes cuestionamientos a la
interpretación de Kuhn, por ejemplo desde la biología (Mayr 1995). Como Mayr señala, los
filósofos de la ciencia ponen demasiado énfasis en descubrimientos en desmedro de cambios en
los conceptos.
Sin embargo, la formación de ingenieros durante su etapa de estudios doctorales se basa en el
aprendizaje de los aportes mencionados de la filosofía de la ciencia, y se pretende que el
aprendiz extraiga sus propias conclusiones sobre su campo de interés. Allí es donde se nota la
falta de estudios específicos que se refieran a teorías construidas en las ciencias de la ingeniería.
La motivación de este estudio ha sido proveer un estudio de caso sobre el cambio teórico dentro
de la mecánica aplicada, en particular referido a la teoría de estabilidad de sólidos elásticos.
La historia de la teoría de estabilidad en el siglo XX representa una situación interesante sobre la
contraposición entre buscar una “cosa” (la carga crítica de pandeo) versus la búsqueda de un
“proceso” (el pasaje de estados críticos a poscríticos). En este trabajo revisaremos primero la
XXIX
teoría clásica de estabilidad estructural y como se produce una crisis conceptual. Describiremos
el período de transición, en el que se buscaron diversas explicaciones a las discrepancias entre
teoría y experimentos, y la nueva teoría basada en la estabilidad poscrítica inicial. Se verá el
proceso de cambio desde la óptica de dos posturas de la epistemología: la de paradigmas de
Kuhn y la de programas de investigación de Lakatos.
El iniciador de la nueva teoría de estabilidad fue Koiter, quien visitó Brasil en dos oportunidades,
en 1983, para dictar un curso de teoría de cáscaras en el LNCC/CNPq, y en 1985, cuando
participó en una reunión de IUTAM y dictó un curso de estabilidad.
LA TEORIA CLASICA
Las características de la teoría clásica
Denominaremos teoría clásica de estabilidad estructural a la vigente en la primera mitad del
Siglo XX, en la cual se cuantificaba una carga de pandeo (o carga crítica, que es un valor escalar)
para evaluar la inestabilidad de una estructura.
A los efectos de llevar a cabo el análisis, la respuesta se computaba a partir de la configuración
descargada y hasta llegar a la carga crítica, que constituía un límite de estabilidad. Era necesario
imponer un modo de deformación adicional (un autovector) para generar la condición de
equilibrio en un estado de equilibrio adyacente. Matemáticamente, la evaluación de la carga
crítica generaba un problema de autovalores para autovectores supuestos en base a
consideraciones físicas. Un buen estado del arte de la teoría clásica fue escrito por Timoshenko
(1936), más adelante actualizado como Timoshenko y Gere (1961).
El éxito de esta teoría estuvo centrado alrededor de la modelación de un caso inicial: la columna
bajo carga axial, para la cual se verificaba experimentalmente que el procedimiento funcionaba.
Debe recordarse que las estructuras prácticas que se construían en esa época (hasta inicios del
siglo XX) se hacían mayormente con estructuras de barras.
Este procedimiento teórico pudo extenderse usando la misma metodología a otras formas
estructurales, incluyendo placas. La metodología de análisis podía llevarse a cabo por dos vías:
en la formulación diferencial se debe
“… suponer que la placa sufre un ligero pandeo bajo la acción de fuerzas aplicadas en su
plano medio, y calcular luego las intensidades que precisan esas fuerzas para mantener la
placa en esa ligera forma de pandeo. La ecuación diferencial de la superficie elástica se
obtiene en ese caso … suponiendo que allí no hay carga lateral.” (Timoshenko, 1936, pp.
353).
Otra vía es usando un método energético, en el cual
“… suponemos que la placa, sometida a tensiones por fuerzas que se ejercen en el plano
medio, experimenta alguna pequeña flexión lateral compatible con las condiciones de
contorno dadas. Esta débil flexión puede originarse sin extensión de ese plano medio y
solamente necesitamos considerar la energía de flexión y el trabajo correspondiente
efectuado por las fuerzas que actúan en la nombrada superficie media. Si el trabajo
realizado por estas fuerzas es menor que el trabajo de deformación por flexión, para cada
XXX
forma posible de pandeo lateral, la forma plana de equilibrio de la placa es estable. Si el
mismo trabajo llega a ser mayor que la energía de flexión para cualquier forma de
deformación lateral, la placa queda en situación inestable y acontece el pandeo”
(Timoshenko, 1936, pp. 354).
Adicionalmente, la metodología se podía también llevar a cáscaras delgadas, para las cuales no
existía aún un campo de aplicación fértil, pero que era de interés mayormente teórico. Por
ejemplo, R. Zoelly estudió en su tesis doctoral de 1915 el problema de esferas de pared delgada
dentro del marco de la teoría clásica, llegando a expresiones sencillas que podían calcularse a
mano para modos simétricos. Timoshenko no encontró objeciones a esa formulación en 1936:
“Hasta ahora hemos considerado únicamente el pandeo simétrico de la lamina pero un
estudio mas general prueba que debido a la simétrica de la lamina esférica comprimida
uniformemente, respecto de cualquier diámetro, la ecuación … deducida de la hipótesis
de simetría … puede utilizarse siempre en el cálculo de la tensión crítica.” (Timoshenko,
1936, pp. 535).
También se lograron expresiones para el cilindro con carga axial y para el cilindro con presión
lateral. La gran ventaja de la formulación clásica estaba asociada a su simplicidad, compatible
con los escasos recursos de cálculo disponibles en esa época. Podría pensarse que el progreso de
los recursos de cálculo se tradujeron en el progreso teórico en este campo. Sin embargo,
notaremos que no fue el ingreso de la computadora sino el cambio conceptual el que posibilitó la
gestación de un nuevo enfoque a la problemática.
La evidencia experimental adversa a la teoría clásica
¿Porqué el enfoque clásico comenzó a mirarse críticamente? El viraje de apreciación estuvo
claramente asociado a la evidencia contraria que se encontró para un caso considerado
importante en su época: el cilindro bajo carga axial.
Si se calculaba la carga critica siguiendo el procedimiento clasico, para un modo de pandeo con
m semiondas en direccion axial y n ondas en direccion circunferencial (representativo de borde
simplemente apoyado) se obtenia una formula muy simple para la tension critica σcr , dada por
σcr = E h /{√[3(1-v)]}
donde a es el radio del cilindro y h el espesor, E el modulo de elasticidad y v el coeficiente de
Poison. El conflicto surgio porque estos σcr son valores mas altos que los que se median en
experimentos de laboratorio sobre modelos en escala reducida, para cilindros de duraluminio, de
acero y de bronce:
“En todos los casos, la falla ocurrió a una tensión mucho menor que la que predice la
teoría. En ningún caso la tensión ultima fue más del 60 % de la teórica” (Timoshenko,
1936, pp. 497-498).
La Figura 243 de Timoshenko (1932) muestra en abscisas la relación entre la carga teórica
clásica calculada y la obtenida en experimentos. En realidad, en muchos casos se obtenían
valores del orden del 15 al 30% del valor que predecía la teoría clásica.
XXXI
“Se observa claramente que la razón de la tensión de ruptura a la teórica decrece cuando
la razón a/h aumenta, es decir que la discrepancia entre el experimento y la teoría es
mayor en las láminas más delgadas” (Timoshenko, 1936, pp. 498).
Este estado de conocimientos generó una gran desconfianza hacia la teoría clásica como forma
de evaluar una carga crítica.
A pesar de que el caso disparador de la crisis fue el cilindro con carga axial, sin embargo la
esfera bajo presión uniforme ofrecía aun mayores dificultades. Siguiendo la teoría clásica, la
carga critica de la esfera era aun mas inadecuada que la del cilindro, pero esto no resulto evidente
sino hasta tiempo después. Las razones asociadas a que la esfera no fuera tomada como un caso
critico pueden ser dos: (i) no habían experimentos confiables sobre esferas, mucho mas
complicados que los del cilindro; y (ii) no había urgencias planteadas desde la industria
aeronáutica para evaluar inestabilidad de esferas.
Otra de las deficiencias de la teoría clásica fue la falta de información sobre la trayectoria
poscrítica:
“La profesión de ingeniería estuvo satisfecha por mucho tiempo con el conocimiento del
límite de estabilidad… Se tomó la posición que, por seguridad, la carga en una estructura
debe siempre mantenerse por debajo de ese limite, haciendo que fuera superfluo
investigar que puede ocurrir por encima de ese límite” (Koiter, 1945, pp. 3).
Esta situación cambió con la necesidad de un mejor aprovechamiento estructural del material:
“En la tecnología moderna, más específicamente en el diseño de aviones en los que la
economía de peso es de gran importancia, esta excedencia de carga límite está
ciertamente permitida!” (Koiter, 1945, pp. 4).
De modo que existía la necesidad de evaluar el comportamiento poscrítico para aprovechar
mejor la capacidad portante de placas, y sin embargo no se contaban con maneras confiables de
computarla.
Nótese que de estos tres problemas señalados (cilindro, esfera y placa) sólo el primero produjo
una crisis en la teoría clásica como para ponerla en jaque.
El rechazo a la teoría y el retorno a la experimentación
Como respuesta operativa ante la falta de acuerdo en cilindro con carga axial, se llevaron a cabo
gran cantidad de experimentos de laboratorio con diferentes niveles de cuidado. Los pioneros
fueron Robertson en 1928, Lundqvist en 1933 y Donnell en 1934, entre otros. Se observó gran
dispersión de los resultados de las cargas máximas que podía alcanzar una cáscara cilíndrica,
pero se observaba una clara tendencia a mayores diferencias entre teoría y cálculo para valores
grandes de la relación a/h (radio/espesor de la cáscara). Los estudios
“… mostraron también que las investigaciones teóricas desarrolladas para una cáscara
cilíndrica ideal pueden ser usadas sólo como una guía para desarrollar formulas empíricas
basadas en numerosos experimentos” (Timoshenko y Gere, 1961, pp. 473).
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Esa desconfianza se extendió a todo modelo teórico en este campo, y la forma de cálculo pasó a
basarse en formulas empíricas obtenidas a partir de los experimentos disponibles. En lugar de
comprender más el fenómeno, los ingenieros se dedicaron a describirlo en más detalle dentro de
los rangos de interés industrial.
LA TRANSICION: CUESTIONAMIENTOS Y EXPLICACIONES EN EL MARCO DE
LA TEORIA CLASICA
Aproximadamente entre 1934 y 1968 hubo intentos de explicar las razones de la discrepancia
entre la teoría clásica y los experimentos. Timoshenko, en la primera edición de su libro, reporta
la siguiente explicación, que le parece satisfactoria:
“Para explicar este desacuerdo, L. H. Donnell anticipó una teoría que tiene en cuenta los
desplazamientos iniciales de la superficie cilíndrica ideal y analizó la flexión de la lamina
debida a esta imperfección inicial, suponiendo que las flechas no son pequeñas. Admitió
también que falla cuando comienza la fluencia del material. Tomando los
desplazamientos iniciales en forma de ondas e igual longitud en las direcciones axial y
circular, combinadas con ondas de pandeo simétrico con respecto del eje, Donnell
encontró que la carga de falla … se puede expresar en función de la razón radio espesor
a/h… Se advierte que existe un acuerdo satisfactorio entre estas curvas y los resultados
de los ensayos” (Timoshenko, 1936, pp. 498-499).
En la segunda edición de su libro, Timoshenko ya no es tan optimista con respecto a la
explicación anterior e incluye más explicaciones alternativas:
“Una investigación adicional para las discrepancias entre teoría y experimentos fue
realizada [por von Karman y Tsien, 1941] estudiando el comportamiento postcrítico de
cáscaras cilíndricas ideales en compresión… Suponiendo pandeo y tomando una
expresión para [el desplazamiento] w con varios parámetros… Vemos que para originar
pandeo en un caso ideal debemos tener una tensión de compresión dada por la ecuación
[clásica], pero con un aumento de la deflexion la carga requerida para mantener la
cáscara cilíndrica en la condición pandeada rápidamente disminuye y se acerca a cerca de
un tercio de la carga de pandeo requerida teóricamente” … “Por eso la flexión comienza
cuando la carga es pequeña y las deflexiones alcanzan los valores a los cuales la
continuación del pandeo requiere de una carga mucho menor que la teórica para el caso
ideal” (Timoshenko y Gere, 1961, pp. 472-473).
Hay también otra explicación disponible de 1950:
“En un siguiente estudio [Donnell y Wang, 1950] de la influencia de imperfecciones en el
proceso de pandeo se supuso que la cáscara cilíndrica tiene inicialmente ondas … Se ve
que la imperfección más pequeña reduce considerablemente la carga máxima que puede
tomar la cáscara cilíndrica en compresión” (Timoshenko y Gere, 1961, pp. 473).
Esos intentos trataban de corregir o mejorar la formulación analítica clásica. En resumen,
podemos señalar las siguientes explicaciones sobre la discrepancia, la mayoría de las cuales
fueron consideradas por Donnell (1976) y Esslinger y Geier (1975):
XXXIII
(a) La teoría clásica de laminas empleada en los modelos no era lo suficientemente exacta. Sin
embargo, se puede demostrar que la influencia de los términos despreciados en la formulación es
pequeña comparada con las grandes discrepancias presentes entre experimentos y teoría, de
manera que esa explicación debió desecharse.
(b) No se había considerado la trayectoria poscrítica del cilindro, que cae después del estado
crítico. Esta explicación de B. Almroth (1963) llevó a evaluar la trayectoria poscrítica e intentar
identificar su punto más bajo como valor de carga de pandeo. En principio se consideraba el
modo crítico y se investigaba la trayectoria poscrítica con deformaciones en ese modo.
“La sensación de satisfacción en el progreso hacia un límite inferior de cargas poscríticas
llegó a un final abrupto cuando Hoff [Hoff, Madsen, y Mayers, 1966] … realizó la
observación que parece que esos cálculos basados en muchos términos de series darán en
definitiva una carga poscrítica nula” (Esslinger y Geier, 1975, pp. 110).
Eso contradecía la evidencia que la carga critica no era nula, de modo que esto hizo abandonar
esa explicación.
(c) Se habían tratado los números de ondas del modo de pandeo supuesto como variables
continuas en lugar de considerárselas como variables enteras. Las investigaciones basadas en
números enteros de ondas (Hoff, Madsen, y Mayers, 1966) mostraban que sobre la trayectoria
poscrítica las cargas no llegaban a cero, y los valores mínimos tenían una cierta concordancia
con los experimentos;
“… sin embargo, la teoría producía un número de curvas y no había criterio para
seleccionar la curva que aparecería en el cilindro real para un largo determinado”
(Esslinger y Geier, 1975, pp. 112).
(d) Las condiciones de contorno analíticas no se satisfacían en los experimentos y viceversa. Este
explicación fue sostenida por J. Singer durante algún tiempo, pero fue abandonada cuando surgió
la teoría de Koiter con fuerza en la década del 70.
“Despreciar la influencia de los bordes… está bien justificada por los propios ensayos, en
los cuales no ocurre una dependencia del fenómeno de pandeo con el algo del cilindro o
con las condiciones de borde. Sin embargo, esto también es aceptable en forma teórica”
(Koiter, 1945, pp. 185).
(e) No se había considerado la posibilidad de que haya un salto de un estado de equilibrio a otro
entre una posición precrítica y una poscrítica. Esta explicación se debe a T. von Karman y H. S.
Tsien (1941).
“Debido a que los desplazamientos supuestos por von Karman y Tsien no pueden
reproducir la solución general en la carga critica, sus resultados para cargas que no se
desvíen excesivamente de la carga de pandeo presumiblemente no son tan buenos”
(Koiter, 1945, pp. 177).
(f) No se habían considerado imperfecciones en la respuesta, que pueden ser la causa de una
caída en la carga teórica de pandeo. El principal estudioso de esta explicación fue Donnell, como
vimos antes.
XXXIV
La teoría clásica coexistió con estas explicaciones durante algún tiempo, y se generaron
expectativas de solucionar las dificultades de la teoría clásica mediante extensiones. Las
evidencias en contra de las explicaciones (a-e) ofrecidas por diversos autores demostraron que no
se podían sostener; sin embargo continuaron vigentes por algún tiempo hasta que finalmente se
desvanecieron en la literatura.
¿Porqué se aceptaron esas explicaciones inadecuadas en su momento? Donnell afirma que se
aceptaban por su conveniencia:
“Esas explicaciones traían beneficios porque les daban a los diseñadores valores
aceptables con el respaldo de una explicación teórica, especialmente (d-e), a pesar de
que: (i) los valores encontrados mediante el uso de esas explicaciones no se
correspondían con los factores reales; (ii) no tenían una justificación real; y (iii)
producían valores demasiado conservadores en algunos casos” … “Sin ese respaldo los
ingenieros hubieran tenido que enfrentar la horrorosa verdad que sus construcciones
tenían diversos defectos que afectaban significativamente su capacidad resistente… Pero
los ingenieros deben vivir y trabajar en un mundo real…” (Donnell, 1976, pp. 394).
Sin conocer la tesis de Koiter, Donnell postuló que (f) era la causa de las discrepancias entre
teoría clásica y experimentos. Esta explicación
“… fue cuestionada por Cox (1940) y por von Karman y Tsien (1941) quienes notaron
que esas desviaciones iniciales deberían ser varias veces mayores que el espesor de la
pared para explicar los valores experimentales bajos; pero esas desviaciones no podrían
haber escapado a que las notaran otros investigadores … Además, Cox y von Karman y
Tsien señalaron que la explicación de Flugge-Donnell requeriría la evolución gradual del
pandeo al aumentar la carga, mientras que los ensayos mostraban un pandeo abrupto y
casi explosivo; tampoco se podían explicar de manera satisfactoria la gran dispersión de
los puntos de los ensayos” (Koiter, 1945, pp. 4).
Había además una explicación extendida cualitativa que servía para tomar en cuenta los casos
que fallaban en la teoría clásica y también los que lo confirmaban (la columna) (Donnell, 1976,
pp. 395).
Ninguno de los trabajos elaborados durante el periodo de transición producían explicaciones
satisfactorias por si mismos o combinados, y por ello no lograron establecer una nueva base
explicativa con un desarrollo teórico aceptable por la comunidad científica en general. Habían
intentos de corregir errores individuales, pero sin reconstruir la teoría clásica. En realidad, no se
trataba de aferrarse a una teoría antigua (como postula Kuhn), sino que nadie sabía como
desarrollar una nueva.
El papel que cumplió la transición fue fundamental: (i) sin ella no habría sido posible recombinar
ideas viejas y sumarles nuevas; (ii) prepararon el campo para generar nuevos términos; (iii)
descartaron posibilidades, que de otra manera hubieran permanecido latentes como explicaciones
alternativas; y (iv) se estableció claramente que había un vacío en el conocimiento, a pesar del
trabajo intenso de los expertos de la época.
XXXV
LA TEORIA DE ESTABILIDAD DE LA REGION POSCRITICA INICIAL
Las características de la nueva teoría
Warner T. Koiter (1914-1997) escribió su tesis doctoral en Holanda en 1945, pero recién en la
década del 60 se difundieron sus trabajos en Estados Unidos y Europa. Koiter señala:
“De los ejemplos anteriores es claro que las teorías de estabilidad formuladas en el
pasado son insuficientes. Deben ser suplementadas de tal manera que aun el
comportamiento de estructuras diferentes, que difieren en la vecindad de la carga de
pandeo teórica, pueda ser descripta” (Koiter, 1945, pp. 4).
Las contribuciones de Koiter constituyen una nueva teoría, desarrollada desde el inicio de
manera sistemática y consistente, con bases matemáticas sólidas y aproximaciones ingenieriles
que se hacen explícitas.
Algunos aspectos salientes de esa teoría son los siguientes:
(a) La formulación está basada en la energía potencial total del sistema estructural, en lugar de
usar consideraciones de equilibrio directo. Por esa vía se rescataban la trayectoria de equilibrio
precrítica y la carga crítica clásica.
(b) Koiter requería de evaluar la trayectoria poscrítica en sus etapas iniciales (a diferencia de
otros estudios de la etapa de transición que precisaban la totalidad de la trayectoria para trabajar).
(c) Matemáticamente, la nueva teoría requiere de un desarrollo en serie de Taylor (o de un
análisis de perturbaciones). También o de un análisis de autovalores y autovectores.
(d) Permitió confirmar las sospechas sobre la importancia de las imperfecciones en la estabilidad
del sistema.
“No sólo que el valor de la carga critica esta influenciado significativamente por las
desviaciones de la estructura con respecto al modelo, sino que la naturaleza del fenómeno
de pandeo es completamente diferente en la estructura y en el modelo” (Koiter, 1945, pp.
92).
(e) Se generó el término “sensibilidad ante imperfecciones”.
(f) Demostró cómo se produce la interacción de modos acoplados en presencia de
imperfecciones pequeñas en la estructura.
Los éxitos de esta teoría están asociados a dos aspectos centrales: Primero, las predicciones de la
nueva teoría se verificaban experimentalmente frente a experimentos realizados antes o con
experimentos nuevos. J. Roorda llevó a cabo experimentos en 1964 para probar los resultados
teóricos de Koiter (Roorda, 1964). En segundo lugar, la nueva teoría lograba explicar y modelar
matemáticamente el comportamiento de casos difíciles (como el cilindro y la esfera) y también
de casos sencillos (la columna). A pesar de que la nueva formulación era complicada, sin
embargo podía usarse sin necesidad de contar con una capacidad de cómputo importante. Koiter
mismo nunca usó computadoras en sus trabajos, y las extensiones para computar su teoría con
XXXVI
elementos finitos ha sido mucho más recientes. Tercero, es posible generalizar la teoría de
manera de llevarla a diversos casos estructurales.
Las ventajas de la teoría incluye el proveer curvas correctas poscríticas en las etapas iniciales,
para desplazamientos menores al espesor de la cáscara, para lo cual se requiere de poco esfuerzo
computacional. Además la teoría provee criterios de estabilidad de la estructura en cualquier
configuración de carga, incluyendo la carga critica. Esto posibilita clasificar los posibles
comportamientos de acuerdo a las trayectorias poscríticas que se generan, o de acuerdo a
indicadores basados en la energía del sistema.
La teoría proveyó una clasificación de los posibles comportamientos esperables en cualquier
estructura. El análisis proveyó los casos de bifurcación estable, inestable, asimétrica y punto de
inflexión, los cuales eran todo lo que le podía ocurrir a un sistema estructural al llegar al estado
critico.
Conceptos previos mantenidos en la teoría de Koiter
Consideremos primero los siguientes interrogantes:
!
!
!
¿Qué quedó de la teoría clásica? En la teoría de Koiter quedaron la carga crítica (como
referente y caso “ideal”, al que no se puede llegar en la práctica) y el modo crítico, que
eran parte de la teoría clásica.
¿Qué cosas nuevas hay que evaluar? En la teoría clásica no era necesario evaluar la
trayectoria poscrítica (inicial), su estabilidad y la sensibilidad ante imperfecciones. Todos
estos elementos son cruciales en la nueva teoría.
¿Qué cosas relaciona la nueva teoría? Relaciona la estabilidad de la trayectoria inicial con
la caída en la carga de pandeo con respecto a la clásica.
Veamos que elementos conocía Koiter durante el desarrollo de su teoría. En primer lugar, Koiter
utilizó el criterio energético para evaluar la estabilidad de un sistema. El criterio mismo no era
nuevo y Koiter cita como caso antecedente a Bryan (1888):
“… Su trabajo parece haber sido el primero en intentar el desarrollo de una teoría general
de estabilidad. Su trabajo se basaba en el criterio energético, que postula que un estado de
equilibrio es estable o inestable dependiendo de si la energía potencial en ese estado tiene
o no un mínimo. Sin embargo sus cálculos de la energía elástica toma en cuenta solo
términos cuadráticos en los desplazamientos. La segunda variación de esta energía
entonces es de la misma forma que la propia energía y es positiva como ella… la segunda
variación de la energía potencial total es también siempre positiva de modo que la
inestabilidad en esos casos queda excluida” (Koiter, 1945, pp. 1).
La principal fuente de la teoría fue, como Koiter mismo señala, los trabajos de Trefftz (1933)
quien uso el criterio energético para evaluar la estabilidad. Pero las limitaciones de estos
enfoques consisten en que al restringir la energía a contribuciones cuadráticas (en lugar de
cuárticas) en función de los desplazamientos sólo era posible considerar el estado neutro de
estabilidad:
“Las consideraciones generales de estabilidad desarrolladas anteriormente y discutidas
aquí estaban restringidas a la investigación de la estabilidad neutra y específicamente
XXXVII
estaban orientadas hacia la determinación del limite de estabilidad. Los fenómenos que
aparecen al alcanzar o aun exceder el limite de estabilidad no eran considerados” (Koiter,
1945, pp. 3).
Un segundo ingrediente tomado por Koiter fue la influencia de imperfecciones pequeñas. Pero
mientras que Donnell consideraba que las imperfecciones se amplificarían al aumentar la carga
hasta que el material entrara en fluencia, Koiter considero la influencia sobre un proceso de
bifurcación, sin introducir plasticidad en la explicación.
Un tercer elemento es el modo de pandeo, que estaba presente en la teoría clásica. Ahora ese
concepto juega un papel central, y la nueva teoría admite modos aislados y también modos
acoplados. En la nueva teoría el modo se puede determinar mediante un análisis de autovectores.
Cuestionamientos y limitaciones de la teoría de Koiter
Cuando la nueva teoría se extendió tuvo que enfrentarse a críticas de otros investigadores. Los
principales cuestionamientos surgidos en la teoría fueron los siguientes:
(a) El comportamiento de una cáscara en la región poscrítica inicial no es un criterio confiable
para predecir su sensibilidad ante imperfecciones (Kempner, 1968). Se encontró un
contraejemplo en este sentido: un cilindro elíptico bajo carga axial tiene un comportamiento que
sigue la teoría de Koiter en su primer carga crítica, pero luego recupera su capacidad portante y
puede ser sometido a cargas mucho mas altas.
(b) No es posible predecir con exactitud la respuesta poscrítica avanzada basándose en la
respuesta poscrítica inicial. Esta limitación surgió como consecuencia del empleo de tecnicas de
perturbación a partir del entorno del estado crítico.
El hecho de evidencia en contra (especialmente el caso de no predecir correctamente la carga de
pandeo del cilindro elíptico) no hizo que la teoría fuera rechazada: “La teoría de Koiter soportó
el ataque y es usada en numerosas publicaciones” (Esslinger y Geier, 1975, pp. 113).
Si bien Koiter mismo sólo trabajó con sistemas continuos, su teoría fue extendida a sistemas
discretos, como se reseña en (Godoy, 2000). Proporcionó un campo fértil sobre el cual se pudo
seguir trabajando. Fue confirmada teóricamente por la teoría de catástrofes en los 70 y 80.
ESTABILIDAD COMPUTACIONAL
La teoría de Koiter ha coexistido con un desarrollo paralelo, que ha usado los términos y nivel de
comprensión logrados por Koiter. El avance en capacidades de computación y el desarrollo de
algoritmos para seguir problemas no lineales hizo que se desarrollara una nueva forma de
trabajo, con menos énfasis en la teoría y mas énfasis en el cómputo.
La estabilidad computacional (Bushnell, 1985) pone énfasis en el cómputo de las trayectorias de
equilibrio usando técnicas numéricas; no usa técnicas de perturbación sino técnicas
incrementales de avance, que son más eficientes. Debemos señalar que la teoría de Koiter
también se puede computar mediante el método de elementos finitos, pero la precisión para el
cálculo de trayectorias poscríticas es menor que en la estrategia de computar trayectorias paso a
paso.
XXXVIII
La motivación detrás de este enfoque ha sido la necesidad de contar con programas de elementos
finitos para usuarios masivos. Desde el punto de vista del usuario, hubo un cambio de énfasis en
la comprensión por uno de descripción. Pero el enfoque computacional al problema de pandeo
también tiene sus limitaciones: por ejemplo, los algoritmos pasan por alto los puntos críticos, les
cuesta cambiar de trayectorias, no proveen información sobre la estabilidad misma de los estados
de equilibrio. En todas las soluciones intentadas se vuelve a la teoría de Koiter (por ejemplo, para
cambios de trayectoria se usan perturbaciones hasta encontrar un estado de equilibrio).
LA VISIÓN DE PARADIGMAS Y REVOLUCIONES DE KUHN
En esta sección no intentaremos describir la teoría de Kuhn sobre el cambio científico, dado que
esa tarea escapa a las limitaciones de un trabajo y a las posibilidades del autor. La versión
original de este enfoque se encuentra en Kuhn (1962), mientras que una versión modificada fue
presentada en Kuhn (1981). En lugar de eso supondremos cierta familiaridad del lector con la
teoría de Kuhn y pasaremos a ilustrar de que manera esa teoría permite interpretar la situación de
la estabilidad elástica al cambiar del enfoque clásico al nuevo.
La identificación de paradigmas en la teoría de estabilidad
Un aspecto central en el análisis de Kuhn es el de paradigma. El concepto mismo de paradigma
no es fácilmente definible, como han notado muchos filósofos de la ciencia, dado se incluyen allí
los supuestos teóricos, las leyes y las técnicas para su aplicación que los miembros de una
comunidad científica adoptan en un momento determinado. Kuhn explicita el papel
desempeñado por un paradigma como vehículo para la teoría científica:
“…su función es la de decir a los científicos que entidades contiene y no contiene la
naturaleza y como se comportan esas entidades. Esta información proporciona un mapa
cuyos detalles son elucidados por medio de las investigaciones científicas avanzadas…
este mapa es tan esencial como la observación y la experimentación para el desarrollo
continuo de la ciencia… Al aprender un paradigma, el científico adquiere al mismo
tiempo teoría, métodos y normas, casi siempre en una mezcla inseparable” (Kuhn, 1962,
pp. 173-174).
Lo primero que nos preguntamos es si las teorías clásica y poscrítica inicial llegan a constituir
paradigmas en la concepción de Kuhn. Esto también permitirá establecer si ha habido realmente
un cambio de paradigma.
Podemos afirmar que la teoría clásica fue el paradigma fundacional en la disciplina. Timoshenko
explica el estado de situación hacia 1936:
“Necesidades prácticas de carácter urgente originaron en los últimos años amplias
investigaciones teóricas y experimentales acerca de las condiciones que rigen la
estabilidad de los elementos comprimidos… Parece haber llegado el momento en que
esos trabajos, conservados en diferentes lugares y en distintos idiomas, y que son con
frecuencia de difícil acceso para los ingenieros que los precisan como normas de sus
proyectos, se compilen y lleguen a formar un libro” (Timoshenko, 1936, Prologo).
XXXIX
El nombre dado por Timoshenko a su libro de 1936, “Teoría de estabilidad elástica”, pasó a
identificar el área de trabajo y se constituyó en el referente para todos aquellos que practicaban la
especialidad o eran usuarios de ella. Trabajar en esta área (o paradigma) era contribuir a llenar
los vacíos dejados por el libro, evaluando nuevas cargas críticas de pandeo con la metodología
establecida, tanto experimental como analítica. Esto no significa que no hubiera antes de 1936 un
cuerpo de conocimientos sobre estabilidad, sino que ese era un cuerpo disperso y se constituyó
en paradigma asociado a la contribución de Timoshenko.
Entendemos que uno de los aspectos que pone en evidencia la identidad de un paradigma es el
cambio de nombre de la teoría que lo designa. En el caso que estudiamos, la teoría clásica se
llamaba “Teoría de estabilidad elástica”, mientras que la nueva teoría se identifica como “Teoría
general de estabilidad elástica”. La distinción radica en una palabra (“general”); sin embargo,
tiene las implicancias que la teoría clásica carecía de generalidad, se constituía por medio de una
serie de casos resueltos sin una unidad de principios y sin unidad metodológica. Mas aún, ambas
teorías hacen cosas distintas y buscan entidades distintas, de naturaleza diferente: una cosa (carga
critica) en la teoría clásica, y un proceso (el pasaje del estado crítico al poscrítico) en la nueva
teoría.
Un segundo aspecto constituye la aparición de libros de texto en el proceso revolucionario de la
ciencia:
“… puesto que los libros de texto son vehículos pedagógicos para la perpetuación de la
ciencia normal, siempre que cambien el lenguaje, la estructura de problemas o las normas
de la ciencia normal, tiene, íntegramente o en parte, que volver a escribirse … Así pues,
los libros de texto comienzan truncando el sentido de los científicos sobre la historia de
su propia disciplina y, a continuación, proporcionan un sustituto para lo que han
eliminado” (Kuhn, 1962, pp. 214).
Un tercer aspecto es la redefinición de la historia que condujo al paradigma y de la galería de
héroes:
“Por razones que son obvias y muy funcionales, los libros de texto científicos… se
refieren sólo a las partes del trabajo de científicos del pasado que pueden verse fácilmente
como contribuciones al enunciado y a la solución de problemas paradigmaticos de los
libros de texto. En parte por selección y en parte por distorsión, los científicos de épocas
anteriores son representados implícitamente como si hubieran trabajado sobre el mismo
conjunto de problemas fijos y de acuerdo con el mismo conjunto de cánones fijos que la
revolución mas reciente en teoría y metodología científica haya hecho presentar como
científicas” (Kuhn, 1962, pp. 215).
Es interesante observar que el nombre de Henry Poincaré, quien trabajó hacia finales del siglo
XIX, no aparece citado en ninguna de las ediciones de Timoshenko; sin embargo, es parte de la
historia recuperada en los libros del nuevo paradigma (Thompson y Hunt, 1973), porque a él se
remontan las técnicas de perturbación, necesarias en la teoría poscrítica inicial pero no en la
clásica. Algo similar ocurre con Lyapunov, quien sentó las bases para comprender el concepto de
estabilidad; pero ese concepto aparece como marginal en la teoría vieja y como central en la
nueva. Y de Trefftz, quien desarrolló el método energético. Por lo tanto hay una redefinición de
quienes son los precursores en el área de trabajo.
XL
Un cuarto aspecto es que la nueva teoría no está formada por correcciones a la teoría clásica; esto
se había intentado en el periodo que denominamos de transición, pero sin éxitos significativos
porque no se avanzó en la comprensión de los fenómenos no explicados o anomalías. La nueva
teoría debe comenzar definiendo axiomas y construye conocimientos de una manera más
sistemática que en la teoría vieja.
Postulamos aquí que hay dos paradigmas bien establecidos, y que hubo un verdadero cambio de
paradigma entre la teoría clásica y la poscrítica inicial; sin embargo, veremos que las
consecuencias de ese cambio no son tal como las describe Kuhn sino que presentan otros
matices. Además, el nuevo paradigma nunca adquirió el monopolio, de manera que han
subsistido ambos paradigmas aunque a veces entren en conflicto.
Anomalías
Kuhn menciona que los descubrimientos de los que surgen nuevos tipos de fenómenos presentan
algunas características:
“…la percepción previa de la anomalía, la aparición gradual y simultánea del
reconocimiento tanto conceptual como de observación y el cambio consiguiente de las
categorías y los procedimientos del paradigma, acompañados a menudo por resistencias”
(Kuhn, 1962, pp. 107).
Consideremos dos anomalías vistas en las secciones anteriores. Entendemos que la teoría de
Kuhn permite acomodar adecuadamente ambos casos, cuyo resultado fue diferente. Por el
contrario, el concepto de anomalía no aparece explícitamente en Lakatos.
(a) La anomalía del cilindro con carga axial hizo tambalear a la teoría clásica. Esta puede
interpretarse en el marco siguiente:
“…una anomalía sin aparente importancia fundamental puede provocar una crisis si las
aplicaciones que inhibe tiene una importancia práctica particular…” (Kuhn, 1962, pp.
135-136).
Vale decir, la anomalía es significativa por no permitir predecir adecuadamente la inestabilidad
de un problema urgente para la industria aeronáutica. Pero hay otra característica más de esta
anomalía, que pertenece al grupo de
“…las anomalías reconocidas cuyo rasgo característico es su negativa tenaz a ser
asimiladas en los paradigmas existentes” (Kuhn, 1962, pp. 157).
En este sentido vimos como fue difícil para los investigadores de la transición poder explicar las
discrepancias anómalas como parte de la teoría clásica.
(b) La anomalía del cilindro elíptico bajo carga axial, por el contrario, no hizo temblar a la teoría
de Koiter. ¿Que diferencia hay con la anterior anomalía?
“Aparentemente, tampoco había parecido lo suficientemente importante como para
provocar el malestar que acompaña las crisis; pudiendo reconocerse como ejemplos en
contrario y, no obstante, ser relegados para un trabajo posterior” (Kuhn, 1962, pp. 135).
XLI
De manera que la anomalía del cilindro elíptico cayo en un lugar latente: se comprendía porque
la teoría no lo podía tomar en cuenta, pero no se contaba con un remedio que lo permitiera
incluir adecuadamente. Esa paso a ser una de las limitaciones de la nueva teoría, que se
concentraba en la vecindad del estado crítico y no llegaba mas lejos, como lo hace la estabilidad
computacional.
El cambio de términos y conceptos entre paradigmas
Kuhn acierta al decir que los términos no se aprenden separados o aislados, sino que vienen en
grupo y es allí donde toman sentido. Los conceptos que existían antes de la nueva teoría incluían
la carga crítica, el modo de pandeo, y en el periodo de transición habían llegado a incorporar la
trayectoria poscrítica, pero eso no bastó para acomodar los cambios revolucionarios. Lo nuevo
(Koiter) no se puede describir completamente en términos de lo viejo (teoría clásica). Antes no
había conceptos construidos para estabilidad poscrítica inicial, ni para sensibilidad ante
imperfecciones. Por ejemplo, Donnell había introducido en esta área de la ciencia el término de
imperfección, pero no con el enfoque de Koiter, que le dio un viraje nuevo. Por lo tanto, hay un
vocabulario nuevo, términos nuevos y conceptos nuevos. Eso no excluye que esos nuevos
términos no hayan sido aprendidos por los investigadores que continuaron trabajando en la teoría
clásica.
El concepto de modo en la teoría clásica era una forma única e interesaba sólo como paso
intermedio para llegar a la carga crítica. En la versión de Donnell se hablaba del modo
postcrítico, pero también como forma inmutable. Mucho después se introduce la idea que el
modo postcrítico puede evolucionar a medida que avanza el proceso de deformación. Koiter
recupera tanto el modo único como el acoplado, no como forma de evaluar la trayectoria
poscrítica avanzada sino sólo como manera de tomar una dirección de deformación hacia la cual
la estructura tendería al inicio de los estados poscríticos.
Si bien previamente ya había conceptos de estabilidad debidos a Lyapunov, Koiter incluyó la
estabilidad en el sentido de Trefftz, como término predictivo que forma parte del análisis.
Entonces la estabilidad deja de ser una cualidad teórica secundaria y pasa a ser un elemento útil
para la clasificación. La clasificación del comportamiento no era posible (ni se vislumbraba)
antes de Koiter. La nueva teoría toma un carácter holista al clasificar los tipos de
comportamiento posibles. Como tal, da una estructura a la teoría.
En la nueva teoría, algunos términos, como modo de pandeo y estabilidad, se conectan con la
física del problema de una manera distinta. Y esto altera el conjunto de situaciones con las que se
relacionan estos conceptos. Los problemas de traducción se ven facilitados enormemente por la
transición, que incorpora términos necesarios para el nuevo enfoque, como los de trayectoria
poscrítica e imperfecciones. Quizás términos como carga crítica ya no son idénticos, pierden el
carácter predictivo que tenían en la teoría clásica y ahora adquieren un carácter de referencia,
pasan a ser un valor en el cual apoyarse y son útiles para buscar un nuevo término que si tenga
carácter predictivo. Ese nuevo término es la carga máxima (evaluada en la trayectoria imperfecta
no lineal) que sólo adquiere sentido en conjunto con imperfecciones, respuesta inicial y
estabilidad del estado crítico.
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¿Hay revolución en el sentido de Kuhn?
El concepto de revolución de Kuhn ha sido duramente criticado desde la óptica de la biología.
Según Mayr (1995), en biología no hay revoluciones en el sentido de Kuhn. Por ejemplo, en la
clasificación sistemática no hubo una sustitución revolucionaria porque los dos paradigmas se
siguieron usando. Mayr señala:
“No hubo una revolución en la que se rechazara la ciencia anterior. No hubo paradigmas
inconmensurables” (Mayr, 1995, pp. 115).
En la teoría de estabilidad aún hoy los programas de computadora para propósitos generales que
usan elementos finitos, pueden calcular tanto las cargas críticas (teoría clásica) como las
trayectorias no lineales (teoría poscrítica). Es del conjunto de enfoques que el ingeniero
interpreta la realidad o toma decisiones, y asigna a cada elemento de juicio un peso para
interpretar su objeto de estudio.
En la teoría de estabilidad es claro que hubo una revolución, pero no un cambio repentino como
dice Kuhn, ni tampoco irracional y excluyente. El conflicto entre paradigmas ciertamente existe
en la teoría de estabilidad
“Así pues, es evidente que debe haber un conflicto entre el paradigma que descubre una
anomalía y el que, más tarde, hace que la anomalía resulte normal dentro de las nuevas
reglas” (Kuhn, 1962, pp. 156).
Pero eso no hace que ambos paradigmas resulten mutuamente excluyentes, como pretende Kuhn
por ejemplo en este párrafo:
“Por consiguiente, demos ahora por sentado que las diferencias entre paradigmas
sucesivos son necesarias e irreconciliables” (Kuhn, 1962, pp. 165).
Tampoco es cierta la imagen de revoluciones cortas y bien definidas con largos periodos
intermedios de ciencia normal. La teoría clásica de estabilidad se consolidó como paradigma
alrededor de 1936, pero casi coincidentemente se inició el periodo de transición en la búsqueda
de solución de la anomalía del cilindro, que duró alrededor de 30 años. Nunca hubo cambio
irracional del punto de vista de los científicos, basados en cuestiones de valores, sino que los
científicos lograron ver el campo formado por dos paradigmas que coexisten aún. Siempre fue
posible comparar los paradigmas entre ellos, y no han sido imposibles la traducción y la
interpretación.
Nos queda siempre, por cierto, la alternativa de sólo llamar revoluciones en la terminología de
Kuhn, a aquellas que cumplan con los requisitos que él señala, incluyendo (i) que “los
proponentes de paradigmas que están en competencia estarán a menudo en desacuerdo con
respecto a la lista de problemas que cualquier candidato a paradigma deba resolver”; (ii) que “en
el nuevo paradigma, los términos, los conceptos y los experimentos antiguos entran en relaciones
diferentes unos con otros”; y (iii) que “quienes proponen los paradigmas en competencia
practican sus profesiones en mundos diferentes… ven cosas diferentes y las ven en relaciones
distintas unas con otras” (Kuhn, 1962, pp. 230-233). Pero esta alternativa no parece estar en
acuerdo con la ciencia real a la que se trata de comprender. Notamos que los puntos (i) y (iii) son
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los más conflictivos y alejados de la realidad de la teoría de estabilidad. Consideremos estos
aspectos en más detalle.
Por ejemplo, tomemos un científico cuya práctica de investigación está centrada en la teoría
clásica, y le interesa principalmente evaluar cargas criticas clásicas en sistemas no clásicos,
como elementos estructurales construidos con materiales compuestos (composites). Un artículo
que deba ser revisado por otro científico inmerso en la teoría poscrítica encontrará que sólo le
están contando parte de la historia, y que el estudio es preliminar y está incompleto. Pero no
desechará la información provista por errónea, sino por incompleta y que puede llevar a
conclusiones equivocadas. Tampoco ambos científicos viven en mundos conceptuales diferentes,
porque muy probablemente ambos conozcan acerca de los dos paradigmas, sino que su práctica
transita por caminos que terminan en lugares diferentes. Lo que para el primer científico es
“trabajo a ser realizado en un futuro”, para el segundo es “trabajo aún no realizado”.
Sobre los científicos que generan el nuevo paradigma
Este es un tema marginal en Kuhn, pero el caso de Koiter parece corresponderse bien con el
siguiente párrafo de Kuhn:
“Casi siempre, los hombres que realizan esos inventos fundamentales de un nuevo
paradigma han sido muy jóvenes o muy noveles en el campo cuyo paradigma cambian…
se trata de hombres que, al no estar comprometidos con las reglas tradicionales de la
ciencia normal debido a que tienen poca práctica anterior, tiene muchas probabilidades de
ver que esas reglas no definen ya un juego que pueda continuar adelante y de concebir
otro conjunto que pueda reemplazarlas” (Kuhn, 1962, pp. 146-147).
La situación de Koiter al buscar su tema de tesis fue descripta así por él mismo:
“Llegué a la conclusión que valía la pena escribir una tesis doctoral en las noches… Al
año siguiente imaginé que había encontrado una base adecuada, el teorema que el
dominio estable en el espacio de carga de una estructura elástica con un estado precrítico
lineal es siempre convexo. Fue desalentador cuando descubrí algo mas tarde que
Papkovich había publicado este teorema en 1934…” (Koiter, 1979, pp. 243).
Esto ilustra que Koiter era un recién llegado al campo y no tenia el tipo de compromiso con las
reglas tradicionales de la teoría clásica. Aunque no se trata de algo central en la visión de Kuhn,
el papel que cumplen los forjadores de un paradigma aparece acertadamente descripto en nuestro
caso.
LA VISIÓN DE LOS PROGRAMAS DE INVESTIGACIÓN DE LAKATOS
Podemos analizar el cambio teórico de la teoría clásica a la de Koiter desde el punto de vista de
los programas de investigación. Siguiendo a Lakatos (1978), podemos decir que existió un
programa de investigación regresivo, basado en el concepto de carga crítica clásica, el cual fue
progresivo en el momento en que se aplicó solamente a columnas y placas, pero que se convirtió
en regresivo al abordar problemas de algunas cáscaras. Hay un cambio racional, y está basado en
el poder explicativo del nuevo programa.
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El enfoque de Lakatos permite una mejor caracterización de la estructura de los programas con
respecto a la caracterización indefinida de la estructura de los paradigmas en Kuhn.
El núcleo firme
Según Lakatos, en el núcleo firme se define el conocimiento fundamental no problemático, las
leyes básicas del programa. En el núcleo firme del programa de Koiter, los postulados básicos
son
(a) Los axiomas de equilibrio y estabilidad de sistemas elásticos, basados en la energía potencial
total. Estos axiomas no pueden someterse a cuestionamiento porque están tomados como el
núcleo que se va a defender. Tampoco pueden demostrarse de manera independiente. Como
sustento requieren de usar trabajos virtuales para sistemas continuos, y no tienen ni ese apoyo
para sistemas discretos.
(b) La estabilidad del sistema en el estado crítico (que se calcula en base a derivadas superiores
de la energía) determina si la trayectoria poscrítica en su parte inicial (desplazamientos muy
pequeños) existe para valores crecientes de la carga o sólo para valores decrecientes. Koiter
señala esto así:
“Esto lleva a la sospecha que la diferencia en el comportamiento elástico de diferentes
estructuras con cargas cercanas a la carga teórica de pandeo esta conectado con el
carácter diferente de los posibles estados de equilibrio vecinos correspondientes a esas
cargas” (Koiter, 1945, pp. 5).
(c) Para pequeñas irregularidades en el sistema el estado precrítico se perturba y da una carga
máxima (menor que la crítica cuando el estado crítico mismo es inestable) que se puede evaluar
mediante un análisis de perturbación del comportamiento perfecto.
El cinturón protector
Las hipótesis auxiliares que defienden el núcleo se construyen de manera ecléctica. En la versión
de Koiter, la teoría de estabilidad elástica incluye un cinturón protector constituido por varios
elementos:
(a) Se considera que las componentes estructurales más eficientes son de una dimensión o de dos
dimensiones, con tensiones aproximadamente constantes en la sección transversal o en el espesor
(estado membranal), para los que el pandeo ocurre de manera de bifurcación.
(b) Se considera que se puede usar el tensor de Cauchy de tensiones conjuntamente con el tensor
de deformaciones de Green-Lagrange, lo cual es estrictamente inconsistente. Pero según Koiter,
“En muchos problemas de pandeo podemos ignorar la diferencia entre las coordenadas
cartesianas en la estructura indeformada y en el estado fundamental como variables
independientes” (Koiter, 1982).
(c) Koiter usa una teoría simplificada de cáscaras, para cáscaras rebajadas:
XLV
“Para cáscaras el comportamiento mas característico de pandeo ocurre en modos de
pandeo rebajados, cuya longitud de onda mínima L es pequeña comparada con el radio de
curvatura más pequeño de la superficie media” (Koiter, 1982).
Estas hipótesis auxiliares que hace Koiter podrían ser removidas si hiciera falta, pero a él le
parecen razonables. Lejos de ser parte del núcleo central, estas condiciones pueden ser atacadas
por otros autores y podrían estar sujetas a ajustes sin perjuicio del núcleo central.
La heurística
La heurística es la maquinaria para la solución de problemas en la teoría. Se ayuda de técnicas
matemáticas y consiste en reglas metodológicas. La heurística positiva avanza sin importarle lo
que dice la evidencia en contra, como los resultados adversos del cilindro elíptico o del cilindro
con agujeros.
Como heurística importante la nueva teoría usa la técnica de perturbaciones. Thompson y otros
investigadores enriquecen la heurística al asumir sistemas con múltiples grados de libertad
(Thompson y Hunt, 1973), de modo que incorporan al método de elementos finitos como técnica
de solución.
El cambio de programas
En el enfoque de Lakatos el cambio de programa de investigación comienza cuando el viejo
programa se vuelve regresivo, o sea cuando la teoría se comienza a fabricar para acomodarse a
los hechos. Se manufacturan hipótesis auxiliares después de los acontecimientos para proteger a
la teoría de los hechos. Se atrasa con relación a los hechos y el programa regresivo corre detrás
de los hechos para alcanzarlos. Esta situación regresiva se encuentra fácilmente en la teoría
clásica de estabilidad, lo cual pone en evidencia una gran desconfianza en sus postulados y
predicciones.
La teoría de Koiter por el contrario, es progresiva. Explica los fenómenos no explicados en la
teoría anterior, y conduce a descubrir hechos o fenómenos nuevos. Por ejemplo, conduce a
descubrir el acoplamiento de modos, ignorado hasta ese momento. El nuevo programa logro
predecir hecho nuevos muy rápidamente una vez que fue aceptado por un grupo significativo
(aunque no completo ni mayoritario) de científicos.
La historia externa
La historia en Lakatos contiene una historia interna y una externa. Lo que hemos narrado
anteriormente es parte de la historia interna, formada por la explicación racional del crecimiento
del conocimiento objetivo.
La historia externa es la historia sociológica y social de la ciencia. Aquí interesa
fundamentalmente considerar la participación de Koiter, que produjo un cambio en la
perspectiva desde la cual se podía ver el problema de estabilidad. Afortunadamente la situación
de Koiter se encuentra documentada en sus escritos (Koiter, 1979) y en las conferencias que
dictó en Río de Janeiro en 19831.
______________________________
1
Tuvimos ocasión de participar en dos cursos dictados por Koiter en LNCC en 1983 y 1985.
XLVI
“En la primavera de 1940 tuve la mala fortuna de caer con neumonía y pleuresía y casi no
pude salir de cama cuando ocurrió la invasión Nazi el 10 de mayo. Sin embargo, en cama
leí un artículo estimulante por Leslie Cox… y su tratamiento simple del comportamiento
de una columna con un apoyo no lineal elástico me sugirió la idea básica que la
inestabilidad en la carga crítica podría ser la explicación del desastroso efecto de
imperfecciones. Esta conjetura me llevó al desarrollo de la teoría general de estabilidad
elástica no lineal en mi tesis… El trabajo básico, incluyendo la aplicación del
sorprendente problema de pandeo de cáscaras cilíndricas bajo compresión axial, fue
completado en febrero de 1942” (Koiter, 1979, pp. 243).
El idioma en el cual fue escrita la tesis sin duda influyó en sus posibilidades de impacto:
“Debido a que el alemán era la única lengua extranjera permitida por los Nazis para
publicaciones, mi manuscrito obviamente sólo podía ser escrito en mi lengua nativa, que
no era fácilmente accesible a la mayoría de mis colegas en el extranjero” (Koiter, 1979,
pp. 243).
La defensa de la tesis fue postergada por Koiter hasta la finalización de la guerra en 1945. La
tesis fue publicada por un editor a quien Koiter estuvo agradecido hasta su retiro, porque le
facilitó demorar la publicación hasta que se produjo el fin de la guerra.
La primera presentación que realizó Koiter sobre estabilidad fue en una conferencia en París en
1946. El tema del trabajo era el pandeo de placas en estados poscríticos avanzados, pero sin
recapitular la teoría que ya había desarrollado. Al parecer, Koiter entendía que ya había
publicado su teoría en la tesis, y que no correspondía reiterar lo dicho otra vez. Las dificultades
de entender la teoría misma, sumado a que estaba presentando un tópico que avanzaba sobre la
teoría, hizo que el trabajo no fuera bien recibido:
“La sesión del congreso en la que presenté un trabajo con algunos resultados numéricos
inesperados fue coordinada por von Mises, quien … cerró la discusión diciendo que el no
creía una palabra del trabajo” (Koiter, 1979, pp. 244).
Con esta mala recepción, Koiter se desanimó y se retiró de este campo, al que sólo volvería para
dictar un curso en Estados Unidos en 1961. El primer trabajo sobre estabilidad publicado por
Koiter en inglés es de 1956 (Koiter, 1956). La primera traducción de su tesis doctoral al inglés
fue publicada por NASA en 1967, pero para esa época había otros científicos trabajando en los
pasos de Koiter. Dos escuelas siguieron a Koiter: la de Harvard, con Budianski y Hutchinson,
quienes continuaron con la formulación continua, y la de Inglaterra (centrada en University
College London) donde se desarrolló la formulación discreta con Thompson y Chilver.
Koiter mismo no desarrolló una escuela en su entorno:
“Una de las serias limitaciones de mi carrera fue que he acompañado sólo unos pocos
estudiantes a su grado doctoral… Una razón … es que en mi trabajo no tenía mucha
necesidad de asistencia por jóvenes asociados” (Koiter, 1979, pp. 240).
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La escuela de Harvard fue también pequeña, pero en University College London se llevó a cabo
un programa extenso de investigación, extendiendo la teoría entre 1965 y 1985. Si bien la
formulación discreta permite la incorporación del método de elementos finitos a la teoría, esto
sólo se realizo en la década de los 80.
La tesis doctoral de Thompson en Cambridge data de 1963. En el prólogo de su primer libro,
Thompson argumenta que su formulación fue desarrollada independientemente de la de Koiter:
“Por varios años el primer autor no tuvo conocimiento de la disertación clásica del Prof.
W. T. Koiter, la cual había permanecido desconocida desde 1945 y sólo recientemente
fue traducida al inglés por la NASA. Esto fue muy afortunado, porque el peso de la
contribución del Prof. Koiter podría haberlo desalentado a seguir con su propio desarrollo
en el tema” (Thompson y Hunt, Prólogo, 1973)
Koiter menciona acerca de las influencias que operó su trabajo en otros investigadores:
“El interés en este campo también floreció en ese tiempo en particular en la Universidad
de Harvard, donde creo que mi trabajo ha tenido alguna influencia, y en University
College en Londres, donde un enfoque similar para sistemas elásticos discretos fue
desarrollado de manera mas o menos independiente, como se describe tan
elocuentemente en el prefacio de la monografía de Thompson y Hunt…” (Koiter, 1979,
pp. 244).
La historia externa explica porqué el trabajo de Koiter permaneció sin conocerse entre 1945 y
1961, y sólo con muchas restricciones a partir de ese momento. Las dificultades teóricas
asociadas a la teoría misma fueron un escollo a su divulgación generalizada, que siempre
permaneció limitada a un grupo de estudiosos que podían dedicar el tiempo necesario para su
comprensión.
EL CAMBIO EPISTEMOLOGICO EN LA TEORÍA DE ESTABILIDAD
Una de las utilidades del enfoque epistemológico es que nos ayuda a seguir aspectos de las
teorías que de otra forma podrían pasarnos desapercibidos. En este caso hemos prestado atención
a dos enfoques de la filosofía de la ciencia, asociados a la interpretación de paradigmas
científicos y a la de programas de investigación. Algunas de las conclusiones importantes que
surgen de esta mirada pueden resumirse de la siguiente manera.
(a) Resulta útil visualizar de una manera más general las teorías dentro del marco de paradigmas
o programas. La riqueza descriptiva de los programas de investigación parece más adecuada para
las teorías de las ciencias de la ingeniería, al incluir una estructura explícita. Esa estructura
explícita (núcleo, cinturón, heurística) es además identificable en el caso de las teorías de
estabilidad. El concepto de paradigma es más elusivo y no nos ayuda tanto a estructurar la teoría
analizada.
(b) Entendemos que las crisis de las teorías en ciencias de la ingeniería se generan cuando se
identifican sus límites y se encuentran problemas que no pueden predecir correctamente un
comportamiento importante. Pero no porque el problema sea conceptualmente crucial (como
pretendía Bacon y los empiristas) o porque se haya identificado una forma de falsación, como
pretendía Popper (1969), sino porque la limitación encontrada es significativa en el contexto de
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aplicación. Por eso la teoría clásica de estabilidad entró en crisis, al encontrar serias limitaciones
en problemas significativos (cilindro con carga axial, significativo en la industria aeronáutica).
(c) El papel de las anomalías en el cambio de teoría aparece ilustrado en nuestro estudio de
estabilidad. El problema del cilindro bajo carga axial, ¿fue planteado como un caso de falsación,
en el sentido de Popper? Claramente no. Nadie diseñó ese caso como un experimento crucial con
la intención de falsar la teoría. Como menciona Timoshenko (1936), se debió al uso de cáscaras
delgadas en estructuras aeronáuticas, que necesitaban de un nivel de seguridad alto y por ello
indujeron a los ingenieros a realizar experimentos para tener confirmaciones independientes de
los valores teóricos. La sorpresa fue encontrar diferencias tan grandes entre experimentos y
cálculos. El motor de curiosidad fue la demanda de una industria, ampliando las fronteras de las
necesidades, las que llevaron a pasar de columnas a cáscaras como tema de interés.
Sin embargo, cuando Kempner encontró falencias en la teoría de Koiter (el problema del cilindro
elíptico en compresión), esta no entra en crisis porque el problema no es significativo como
necesidad industrial, sino sólo es un contraejemplo y puede ser tratado como una anomalía. En
definitiva, se genera una hipótesis ad-hoc (la teoría no puede aplicarse en ese tipo de casos).
En las ingenierías el conocimiento está atado a su significación en cuanto a las necesidades que
logra satisfacer. Eso hace que necesariamente requiera de un marco histórico y uno de
aplicación. El conocimiento no puede separarse de la aplicación, porque sino deja de tener
significación.
(d) El periodo de transición juega un papel fundamental en el cambio teórico, no tanto porque los
investigadores involucrados acumulen conocimientos hasta encontrar una nueva formulación,
sino porque permite incorporar términos y conceptos nuevos útiles en la nueva teoría, aunque de
una manera diferente. En nuestro ejemplo la transición aparece similar a lo descripto por
Lakatos.
(e) El lugar de las revoluciones ha sido siempre conflictivo en la nueva filosofía de la ciencia. En
nuestro caso hubo un cambio revolucionario; sin embargo ese cambio no tuvo la forma de una
conversión en masa al nuevo paradigma, con la desaparición del viejo paradigma. Por el
contrario, han seguido coexistiendo ambos paradigmas, aunque dentro de un marco mas general
en el que se reconocen las limitaciones del paradigma viejo. Esto es evidente en los programas
para propósitos generales de elementos finitos, en los que coexisten los algoritmos de calculo de
carga crítica con los de evaluación de trayectorias no lineales que tiene sentido en la
interpretación de Koiter.
AGRADECIMIENTOS
Este trabajo no habría sido posible sin el aporte de los colegas y profesores en University College
London durante el periodo de 1975-1979. También agradecemos las enseñanzas de Koiter
durante 1983 y 1985 en Río de Janeiro, y los comentarios que realizó en reuniones más
informales.
XLIX
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AIAA Journal
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Optimized nonuniform rational b-spline geometrical representation for aerodynamic design of wings
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Lepine J. Guibault F. Trepanier JY. Pepin F.
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Coupled analytical sensitivity analysis and optimization of three-dimensional nonlinear aeroelastic systems
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Required relationship between objective function and pareto frontier orders: practical implications
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Probe diagnostics of gas discharges in supersonic airows
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2227
Free vibrations of an orthotropic thin cylindrical shell on a pasternak foundation
Stochastic nite element analysis of beam with statistical uncertainties
Exact and accurate solutions in the approximate reanalysis of structures
Detection of multiple damages by prestack reverse-time migration
Advanced algebraic model for turbulent diusion vector in two-equation turbulence models
Parallel performance analysis of fvtd computational electromagnetics code
Prediction of separation angles induced by sharp ns with attack angle
Dynamics of an orbiting exible beam with a moving mass
Cyclic creep of piezoelectric polymer polyvinylidene uoride
Maute K. Nikbay A. Farhat C.
Simonich JC. Narayanan S. Barber TJ.
Nishimura M.
Rasetarinera P. Kopriva DA. Hussaini MY.
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Yang JY. Perng YC. Yen RH.
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Yang JC. Chang KC.
Gaitonde DV.
Daniel E. Thevand N.
Grasso F. Marini M. Ranuzzi G. Cuttica S.
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Kriging models for global approximation in simulation-based multidisciplinary
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Detection and repair of poorly converged optimization runs
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Evaluation of damage tolerance analysis tools for lap joints
Far-eld calculations for turbofan noise
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Numerical simulation of jets in a crossow using dierent turbulence models
Blended ausm plus method for all speeds and all grid aspect ratios
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Modeling of controlled shock-wave/boundary-layer interactions in transonic channel ow
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Fuel-air mixing enhancement by synthetic microjets
Capillary ow in containers of polygonal section
Spacelab experiments on combustion of heptane/hexadecane droplets
Microgravity ignition delay of solid fuels in low-velocity ows
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2351
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Unsteady dynamic variables method for heterogeneous solid propellant burning
Chemistry of jp-10 ignition
Numerical analysis of reducing driver gas contamination in impulse shock tunnels
Suppression of self-sustained oscillations in a supersonic impinging jet
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2382
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Precise time-integration method with dimensional expanding for structural dynamic equations
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Kim H. Papila M. Mason WH. Haftka RT.
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Keimasi MR. Taeibi-Rahni M.
Vierendeels J. Merci B. Dick E.
Rizzetta DP. Visbal MR. Gaitonde DV.
Benay R. Berthouze P. Bur R.
Devenport WJ. Muthanna C. Ma RL. Glegg
SAL.
Wang H. Menon S.
Weislogel MM.
Shaw BD. Clark BD. Wang DF.
Roslon M. Olenick S. Zhou YY. Walther DC.
Torero JL. Fernandez-Pello AC. Ross HD.
Surzhikov ST. Krier H.
Li SC. Varatharajan B. Williams FA.
Burtschell Y. Cardoso M. Zeitoun DE.
Elavarasan R. Krothapalli A. Venkatakrishnan
L. Lourenco L.
Crouch JD. Miller GD. Spalart PR.
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Johnson ER. Vasiliev VV. Vasiliev DV.
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Geometries for ve-hole-type probes with planar sensor arrays
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Thermal buckling of functionally graded plates
Models of secondary vorticity evolution during normal vortex-cylinder interaction
Two-step method for static topological reanalysis
Assessment of local blowing and suction in a turbulent boundary layer
Surface-shear-stress pulses in adverse-pressure-gradient turbulent boundary layers
Inuence of the wall condition on k-omega turbulence model predictions
Turbulent ow of power-law uids through circular pipes
Periodic vibration of plates with large displacements
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Javaheri R. Eslami MR.
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ow physics
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Suzen YB. Xiong G. Huang PG.
Fitzgerald EJ. Jumper EJ.
Gago CF. Brunet S. Garnier F.
Ozgoren M. Sahin B. Rockwell D.
Ali AH.
Alexandrov NM. Lewis RM.
Phipps C. Luke J.
Seo S. Yoo HH.
Qu ZQ.
Nohmi M. Matsumoto K.
de Almeida SFM. Hansen JS.
Ahn J. Waas AM.
Kim SJ. Lee CS. Kim JH.
Qu ZQ. Selvam RP.
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Sedaghati R. Suleman A. Tabarrok B.
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Thompson DS. Soni BK.
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AIAA Journal
401
408
419
430
438
443
450
456
465
474
481
490
497
501
510
517
526
531
537
545
553
559
566
576
579
582
Aerodynamics of a jet in the vortex wake of a wing
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Dynamics of slender bodies separating from rectangular cavities
Harmonic perturbations in turbulent wakes
Neural network detection of shockwaves
Turbulence models in pulsating ows
EÆcient uncertainty analysis methods for multidisciplinary robust design
Asymptotic theory for laminated piezoelectric circular cylindrical shells
Feasible region in general design space of lamination parameters for laminated
composites
Residual strength prediction of aircraft fuselages using crack-tip opening angle
criterion
Rise of total pressure near the stagnation point on a sphere
Symmetry properties of the transitional sphere wake
New self-referencing pressure-sensitive-paint measurement
40(3) 2002
Wang FY. Zaman KBMQ.
Vahdati M. Sayma AI. Breard C. Imregun M.
Tang DM. Dowell EH.
Narayanan S. Barber TJ. Polak DR.
Mercer CR. Raman G.
Zhuang M. Chen RF.
Ozyoruk Y.
Tam CKW. Pastouchenko NN.
Hu ZW. Morfey CL. Sandham ND.
Oh WS. Kim JS. Kwon OJ.
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Prewitt NC. Belk DM. Shyy W.
Takaki R. Liou MS.
Lee CY. Goldstein DB.
Shalaev VI. Fedorov AV. Malmuth ND.
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585
586
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Applied Mathematical Modelling
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113
141
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Numerical simulation of solids ow in a blast furnace
155
171
191
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Tube erosion modelling in a uidised bed
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223
237
249
263
281
297
311
323
337
351
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industries
26(2 Special Issue SI) 2002
Cleary PW. Sawley ML.
Liovic P. Rudman M. Liow JL.
Zhang SJ. Yu AB. Zulli P. Wright B. Austin
P.
Brown GJ.
Cleary P. Ha J. Alguine V. Nguyen T.
Achim D. Easton AK. Schwarz MP. Witt PJ.
Zakhari A.
Panjkovic V. Truelove J. Ostrovski O.
Lane GL. Schwarz MP. Evans GM.
Freitas CJ.
Taniguchi S. Kawaguchi S. Kikuchi A.
Guo DC. Gu L. Irons GA.
Kahane R. Nguyen T. Schwarz MP.
Witt PJ. Carey KG. Nguyen TV.
Taylor GA. Hughes M. Strusevich N. Pericleous K.
Gardin P. Brunet M. Domgin JF. Pericleous
K.
Pirker S. Gittler P. Pirker H. Lehner J.
Stopford PJ.
Applied Mathematical Modelling
377
397
421
449
473
On coupling electromagnetic elds and lumped circuits with tlm
Multi-domain mass conservative dual reciprocity method for the solution of the
non-newtonian stokes equations
Solidication modelling with a control volume method on domains subjected to
viscoplastic deformation
A numerical and experimental investigation of the modeling of microwave heating
for liquid layers using a rectangular wave guide (eects of natural con vection and
dielectric properties)
Peakons of the camassa-holm equation
26(3) 2002
Mariani AJ. Kirkup SM. Huang Y. Jones GR.
Florez WF. Power H.
Davey K. Rodriguez NJ.
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Applied Mathematics & Mechanics (English Edition)
1231
1240
1252
1260
1268
1273
1279
1291
1301
1306
1311
New principles of work and energy as well as power and energy rate for continuum
eld theories
Study for the bifurcation topological structure and the global complicated character of a kind of nonlinear nance system(i)
Research on the inelastic seismic responses of shear-type multistory buildings
with regular asymmetry
New bifurcation patterns in elementary bifurcation problems with single-side constraint
Investigation of random response of rotational shell when considering geometric
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Boundedness and uniform boundedness results for certain non-autonomous differential equations of fourth order
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Ishikawa iterative process in uniformly smooth banach spaces
A mode-ii griÆth crack in decagonal quasicrystals
5
Zhang YM. Liu QL. Wen BC.
Cui GY. Tai K. Wang BP.
22(11) 2001
Dai TM.
Ma JH. Chen YS.
Cai XH. Wu RF. Xu SB.
Wu ZQ. Chen YS.
Gao SQ. Jin L. Niemann HJ. Liu HP.
Tunc C.
Chen YZ. Hasebe N.
Yuan YR. Liang D. Rui HX.
Chen LQ.
Huang ZY.
Guo YC. Fan TY.
6
1318
1325
1333
1344
1352
The bounds of the general m and j sets and the estimations for the hausdor's
dimension of the general j set
Analytic sensitivity analysis for shape optimization
The smooth and nonsmooth travelling wave solutions in a nonlinear wave equation
The analysis of dynamic stress intensity factor for semi-circular surface crack
using time-domain bem formulation
The extinction behavior of the solutions for a class of reaction-diusion equations
Liu XD. Yan DJ. Zhu WY. Wang GX.
Zhang DX. Jiang YZ. Cai J.
Li SM.
Zhong M. Zhang YY.
Chen SL.
Applied Mathematics & Mechanics (English Edition)
1357
1368
1375
1383
1390
1397
1404
1410
1422
1429
1436
1446
1458
1468
1476
Unied way for dealing with three-dimensional problems of solid elasticity
Complex inner product averaging method for calculating normal form of ode
Study for the bifurcation topological structure and the global complicated character of a kind of nonlinear nance system(ii)
New principles of power and energy rate of incremental rate type for generalized
continuum eld theories
Interval arithmetic and static interval nite element method
A xed point theorem for set-valued mappings
Weighted solution of small-deection buckling equation of thin shell
Study on dynamics, stability and control of multi-body exible structure system
in functional space
Continuation method applied in kinematics of parallel robot
Self-similar solutions of fracture dynamics problems on axially symmetry
Stability analysis of maxwell viscoelastic pipes conveying uid with both ends
simply supported
Linear and nonlinear aerodynamic theory of interaction between exible long
structure and wind
Iterative process for certain nonlinear mappings with lipschitz condition
General expressions of constitutive equations for isotropic elastic damaged materials
Existence and multiplicity of positive solutions for a fourth-order p-laplace equations
22(12) 2001
Xu Q. Sun HC.
Chen YS. Sun HJ.
Ma JH. Chen YS.
Dai TM.
Guo SX. Lu ZZ.
Banerjee A. Singh TB.
Wang ZL. Wang X. Hao WH.
Xu JG. Jia JG.
Dong B. Zhang XD.
Lu NC. Cheng J. Cheng YH. Qu DZ.
Zhao FQ. Wang ZM. Feng ZY. Liu HZ.
Xu X. Cao ZY.
Gu F.
Tang XS. Jiang CP. Zheng JL.
Bai ZB.
Applied Mathematics & Mechanics (English Edition)
1
13
18
26
35
53
58
65
71
79
89
95
100
107
114
Quasi-static and dynamical analysis for viscoelastic timoshenko beam with fractional derivative constitutive relation
The tensor denotation of beltrami spherical vortices and their symmetry analysis
Time precise integration method for constrained nonlinear control system
A family of integrable systems of liouville and lax representation, darboux transformations for its constrained ows
Instability and dispersivity of wave propagation in inelastic saturated/unsaturated porous media
A form invariance of constrained birkhoÆan system
The exact solitary wave solutions for the klein-gordon-schrodinger equations
Stability analysis of hopeld neural networks with time delay
The extension theorems of cone linear operators
Nonlinear saturation of baroclinic instability in the generalized phillips model (i)
- the upper bound on the evolution of disturbance to the nonlinearly unstable
basic ow
The conservation law of nonholonomic system of second-order non-chetave's type
in event space
Exponential stability of interval dynamical system with multidelay
2t-periodic solution for m order neutral type dierential equations with time
delays
Computation of supersonic turbulent oweld with transverse injection
Preliminary analysis of skating motion
23(1) 2002
Zhu ZY. Li GG. Cheng CJ.
Huang YN. Hu X.
Deng ZC. Zhong WX.
Zhang YF. Zhang HQ.
Li XK. Zhang JB. Zhang HW.
Chen XW. Luo SK. Mei FX.
Xia JN. Han SX. Wang ML.
Wang LS. Xu DY.
Sheng BH. Liu SY. Mao H.
Zhang G. Xiang J. Li DH.
Fang JH.
Sun JT. Zhang YP. Liu YQ. Deng FQ.
Zhang BS. Zhu GH.
Sun DC. Hu CB. Cai TM.
Hu H.
Archive for Rational Mechanics & Analysis
1
27
43
65
The scientic life and inuence of cliord ambrose truesdell iii
Stability of spherically symmetric steady states in galactic dynamics against general perturbations
Decay of almost periodic solutions of conservation laws
Wave interactions in nonlinear elastic strings
161(1) 2002
Ball JM. James RD.
Rein G.
Frid H.
Young R.
7
Archive of Applied Mechanics
1
13
39
52
77
Dynamic fracture behavior of a cracked piezoelectric half space under anti-plane
mechanical and in-plane electric impact
Complete eigenfunction expansion form of the green's function for elastic layered
half-space
3d electroelastic elds in a functionally graded piezoceramic hollow sphere under
mechanical and electric loadings
Modeling the response of lled elastomers at nite strains by rigid-rod networks
Morphological stability of epitaxial thin elastic lms by van der waals force
72(1) 2002
Chen ZT. Worswick MJ.
Touhei T.
Chen WQ. Lu Y. Ye GR. Cai JB.
Drozdov AD. Dorfmann A.
Zhao YP.
Communications on Pure & Applied Mathematics
395
431
481
509
Riemann-hilbert problem for the small dispersion limit of the kdv equation and
linear overdetermined systems of euler-poisson-darboux type
Viscosity solutions with shocks
The limit behavior of solutions for the cauchy problem of the complex ginzburglandau equation
The conformal plate buckling equation
55(4) 2002
Grava T.
Giga Y.
Wang BX.
Chanillo S. Kiessling MKH.
Communications on Pure & Applied Mathematics
537
582
633
Vortex dynamics of the full time-dependent ginzburg-landau equations
The limit from the schrodinger-poisson to the vlasov-poisson equations with general data in one dimension
Convexity and all-time c-innity-regularity of the interface in ame propagation
55(5) 2002
Spirn D.
Zhang P. Zheng YX. Mauser NJ.
Daskalopoulos P. Lee KA.
Communications on Pure & Applied Mathematics
395
431
481
509
Riemann-hilbert problem for the small dispersion limit of the kdv equation and
linear overdetermined systems of euler-poisson-darboux type
Viscosity solutions with shocks
The limit behavior of solutions for the cauchy problem of the complex ginzburglandau equation
The conformal plate buckling equation
55(4) 2002
Grava T.
Giga Y.
Wang BX.
Chanillo S. Kiessling MKH.
Communications on Pure & Applied Mathematics
537
582
633
654
Vortex dynamics of the full time-dependent ginzburg-landau equations
The limit from the schrodinger-poisson to the vlasov-poisson equations with general data in one dimension
Convexity and all-time c-innity-regularity of the interface in ame propagation
On the well-posedness of the euler equations in the triebel-lizorkin spaces
55(5) 2002
Spirn D.
Zhang P. Zheng YX. Mauser NJ.
Daskalopoulos P. Lee KA.
Chae D.
Computer Methods in Applied Mechanics & Engineering
1755
1791
1827
1843
1861
1895
1909
Co-rotational beam elements with warping eects in instability problems
Dynamic instability of composite laminated rectangular plates and prismatic
plate structures
Domain-free discretization method for doubly connected domain and its application to simulate natural convection in eccentric annuli
A new locking-free equilibrium mixed element for plane elasticity with continuous
displacement interpolation
Identication of a constitutive model for the simulation of time-dependent interlaminar debonding processes in composites
Discontinuous galerkin methods for incompressible and nearly incompressible
elasticity by nitsche's method
A combined genetic algorithm and nonlinear least squares method for material
characterization using elastic waves
191(17-18) 2002
Battini JM. Pacoste C.
Wang S. Dawe DJ.
Shu C. Wu YL.
Nascimbene R. Venini P.
Corigliano A. Mariani S.
Hansbo P. Larson MG.
Liu GR. Han X. Lam KY.
8
1923
1945
1967
1983
An adaptive procedure based on background cells for meshless methods
A stabilized hybrid-stress solid element for geometrically nonlinear homogeneous
and laminated shell analyses
Lower bound limit analysis by the symmetric galerkin boundary element method
and the complex method
Numerical simulation of the motion of granular material using object-oriented
techniques
Liu GR. Tu ZH.
Sze KY. Zheng SJ.
Zhang XF. Liu YH. Zhao YN. Cen ZZ.
Peters B. Dziugys A.
Computer Methods in Applied Mechanics & Engineering
2011
2029
2045
2069
2077
2095
2111
2141
2159
2179
2191
Mixed nite element method and high-order local articial boundary conditions
for exterior problems of elliptic equation
Parametric analysis of frequency of rotating laminated composite cylindrical shells
with the wave propagation approach
Numerical simulation of delamination growth in curved interfaces
Vibration analysis of orthotropic rectangular plates using superelements
Structural optimization using equivalent static loads at all time intervals
Hierarchical, adaptive, material point method for dynamic energy release rate
calculations
The construction of free-free exibility matrices for multilevel structural analysis
Characterization and design of out-of-ecliptic trajectories using deterministic
crowding genetic algorithms
Weight minimisation of displacement-constrained truss structures using a strain
energy criterion
Hysteresis in ow past a naca 0012 airfoil
Convergence and accuracy of the path integral approach for elastostatics
191(19-20) 2002
Han HD. Zheng CX.
Zhang XM.
Munch A. Ousset Y.
Ahmadian MT. Zangeneh MS.
Choi WS. Park GJ.
Tan HL. Nairn JA.
Felippa CA. Park KC.
Gurl P. Kasdin NJ.
Makris PA. Provatidis CG.
Mittal S. Saxena P.
Pardo E.
Computer Methods in Applied Mechanics & Engineering
2223
2235
2261
2283
2297
2317
2337
2371
2403
2427
An improved reissner-mindlin triangular element
An automated system for simulation and parameter identication of inelastic
constitutive models
On a splitting type algorithm for the numerical realization of contact problems
with coulomb friction
Functionally graded materials for prescribed eld evolution
Analysis of thin piezoelectric solids by the boundary element method
A posteriori error estimates for a mixed-fem formulation of a non-linear elliptic
problem
Boundary cloud method: a combined scattered point/boundary integral approach
for boundary-only analysis
An eÆcient direct bem numerical scheme for phase change problems using fourier
series
On the solution of an inverse scattering problem in seismic while-drilling technology
Reduced bases for model updating in structural dynamics based on constitutive
relation error
191(21-22) 2002
Duan HY. Liang GP.
Furukawa T. Sugata T. Yoshimura S. Homan
M.
Haslinger J. Dostal Z. Kucera R.
Turteltaub S.
Liu YJ. Fan H.
Araya R. Barrios TP. Gatica GN. Heuer N.
Li G. Aluru NR.
Ibanez MT. Power H.
Santos JE.
Deraemaeker A. Ladeveze P. Leconte P.
Computers & Fluids
269
309
335
369
On the combined performance of nonlocal articial boundary conditions with the
new generation of advanced multigrid ow solvers
Numerical solution of optimal magnetic suppression of natural convection in
magneto-hydrodynamic ows by empirical reduction of modes
High-resolution hybrid primitive-conservative upwind schemes for the drift ux
model
An arnoldi approach for generation of reduced-order models for turbomachinery
Computers & Fluids
391
393
Special issue - dedicated to professor roger peyret on the occasion of his 65th
birthday - preface
Special issue - dedicated to professor roger peyret on the occasion of his 65th
birthday - foreword
31(3) 2001
Roberts TW. Sidilkover D. Tsynkov SV.
Park HM. Jung WS.
Fjelde KK. Karlsen KH.
Willcox K. Peraire J. White J.
31(4-7) 2002
Bontoux P. Chattot JJ. Hafez M. Haldenwang
P.
Bontoux P. Chattot JJ. Hafez M. Haldenwang
P.
397
421
437
495
509
On a collocation b-spline method for the solution of the navier-stokes equations
Multilevel stabilization devices in cfd
Numerical modelling of liquid/solid phase transitions - analysis of a gallium melting test
Numerical approximation of one-dimensional stationary diusion equations with
boundary layers
Two adaptive wavelet algorithms for non-linear parabolic partial dierential equations
Numerical investigation of the rst bifurcation for the ow in a rotor-stator cavity
of radial aspect ratio 10
Dns of wall turbulence: dilute polymers and self-sustaining mechanisms
A dual time stepping method for uid-structure interaction problems
539
Computational solution for uid ow under solid/liquid phase change conditions
557
569
Numerical simulation of geophysical turbulence
2d pseudo-spectral parallel navier-stokes simulations of compressible rayleightaylor instability
Dynamically adapted mesh renement for combustion front tracking
Particles and grid
Aspects of unsteady incompressible ow simulations
Residual-based compact schemes for multidimensional hyperbolic systems of conservation laws
Numerical investigation of meniscus deformation and ow in an isothermal liquid
bridge subject to high-frequency vibrations under zero gravity conditions
Numerical simulation of separating boundary-layer ow
A comparison of second- and sixth-order methods for large-eddy simulations
Thirty-six years of shock tting
Performances of upwind methods in predicting shear-like ows
A spectral projection method for the simulation of complex three-dimensional
rotating ows
Explicit methods for the solution of the generalized cauchy-riemann equations
and simulation of inviscid rotational ows
Adaptive and xed segmented domain decomposition multigrid procedures for
internal viscous ows
Filtering of the pressure spurious modes in p-n-p-n spectral approximations of
the stokes system
Spectral methods based on nonclassical basis functions: the advection-diusion
equation
453
467
481
589
607
627
639
663
683
695
719
725
745
769
787
815
825
Botella O.
Canuto C.
Cerimele MM. Mansutti D. Pistella F.
Cheng WF. Temam R.
Chiavassa G. Guichaoua M. Liandrat J.
Daube O. Le Quere P.
De Angelis E. Casciola CM. Piva R.
de Jouette C. Laget O. Le Gouez JM. Viviand
H.
El Ganaoui M. Lamazouade A. Bontoux P.
Morvan D.
Ferziger JH. Kose JR. Monismith SG.
Fournier E. Gauthier S. Renaud F.
Haldenwang P. Pignol D.
Huberson SG. Voutsinas SG.
Kiris C. Kwak D.
Lerat A. Corre C.
Lyubimov DV. Lyubimova TP. Skuridin RV.
Chen G. Roux B.
Marquillie M. Ehrenstein U.
Meinke M. Schroder W. Krause E. Rister T.
Moretti G.
Pandol M. D'Ambrosio D.
Raspo I. Hugues S. Serre E. Randriamampianina A. Bontoux P.
Roy J. Hafez M. Chattot JJ.
Rubin SG. Celestina ML. Srinivasan K.
Sabbah C. Forestier MY. Pasquetti R.
Shizgal BD.
Earthquake Engineering & Structural Dynamics
195
217
445
459
Cyclic analysis and capacity prediction of concrete-lled steel box columns
Structural damage detection using the optimal weights of the approximating articial neural networks
Closed-form solution for seismic response of adjacent buildings with linear
quadratic gaussian controllers
Applicability of the h/v spectral ratio of microtremors in assessing site eects on
seismic motion
Seismic response of rail-counterweight systems in elevators
Analytical model of structures with frictional pendulum isolators
Extraction of hysteretic properties of seismically isolated bridges from quickrelease eld tests
Eect of masonry inlls on seismic performance of a 3-storey r/c frame with
non-seismic detailing
Application of wavelet theory to identify yielding in seismic response of bi-linear
structures
Functional series tarma modelling and simulation of earthquake ground motion
Experimental and analytical studies on the performance of hybrid isolation systems
Performance-based design with semi-active structural control technique
Tests on low-ductility rc frames under high- and low-frequency excitations
475
481
Continuous ambient-vibration monitoring of the arch dam of mauvoisin
Critical damping of structures with elastically supported visco-elastic dampers
235
261
281
305
333
353
379
399
421
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31(2) 2002
Susantha KAS. Ge HB. Usami T.
Hung SL. Kao CY.
Xu YL. Zhang WS.
Rodriguez VHS. Midorikawa S.
Singh MP. Suarez LE. Rildova.
Almazan JL. De la Llera JC.
Chen QB. Douglas BM. Maragakis EA. Buckle
IG.
Lee HS. Woo SW.
Pan TC. Lee CL.
Fouskitakis GN. Fassois SD.
Chang SP. Makris N. Whittaker AS. Thompson ACT.
Kurata N. Kobori T. Koshika N.
Quek ST. Bian CM. Lu XL. Lu WS. Xiong
HB.
Darbre GR. Proulx J.
Lee Y. Takewaki I. Uetani K. Inoue K.
10
Earthquake Engineering & Structural Dynamics
487
491
515
539
561
583
601
627
653
671
693
719
Special topics issue on performance-based earthquake engineering - foreword
Incremental dynamic analysis
Inelastic deformation response of sdof systems subjected to earthquakes
Evaluation of approximate methods to estimate maximum inelastic displacement
demands
A modal pushover analysis procedure for estimating seismic demands for buildings
An estimation of displacement limits for ductile systems
A general framework for risk-consistent seismic design
Performance-based seismic engineering: the need for a reliable conceptual comprehensive approach
Performance evaluation of new steel frame buildings for seismic loads
Generic frame model for simulation of earthquake responses of steel moment
frames
Earthquake-induced oor horizontal accelerations in buildings
A displacement-based approach for the seismic design of continuous concrete
bridges
31(3) 2002
Paulay T.
Vamvatsikos D. Cornell CA.
Riddell R. Garcia JE. Garces E.
Miranda E. Ruiz-Garcia J.
Chopra AK. Goel RK.
Paulay T.
Hadjian AH.
Bertero RD. Bertero VV.
Lee K. Foutch DA.
Nakashima M. Ogawa K. Inoue K.
Rodriguez ME. Restrepo JI. Carr AJ.
Kowalsky MJ.
Earthquake Engineering & Structural Dynamics
749
771
791
813
833
851
881
897
921
937
955
977
993
1007
1025
1033
1037
Tuned mass dampers for response control of torsional buildings
A mathematical hysteretic model for elastomeric isolation bearings
Tangential-projection algorithm for manifold representation in unidentiable
model updating problems
Investigations into critical earthquake load models within deterministic and probabilistic frameworks
Displacement-based seismic analysis for out-of-plane bending of unreinforced masonry walls
Risk assessment of an interacting structure-soil system due to liquefaction
Fuzzy sliding mode control for a building structure based on genetic algorithms
Optimum multiple tuned mass dampers for structures under the ground acceleration based on ddmf and admf
Optimal design of passive energy dissipation systems based on h innity and h-2
performances
A new modelling strategy for the behaviour of shear walls under dynamic loading
Optimal placement of dampers for passive response control
Multiple-tuned liquid column dampers for torsional vibration control of structures: experimental investigation
Simulations of non-stationary frequency content and its importance to seismic
assessment of structures
Probabilistic approach for modal identication using non-stationary noisy response measurements only
Response spectrum of incompatible acceleration, velocity and displacement histories by praveen k. malhotra, earthquake engng struct. dyn. 2001; 30(2): 279-286
Author's reply to discussion by george mylonakis and costis syngros of 'response
spectrum of incompatible acceleration, velocity and displacement histories' earthquake engng struct. dyn. 2001; 30(2): 279-286
Tuned liquid dampers for controlling earthquake response of structures by p.
banerji et al., earthquake engng struct. dyn. 2000;29(5): 587-602
Engineering Structures
385
397
419
429
443
455
469
479
491
Frp-strengthened rc beams. i: review of debonding strength models
Frp-strengthened rc beams. ii: assessment of debonding strength models
Experimental tests on reinforced concrete columns under biaxial quasi-static loading
Mechanical properties of structural bamboo for bamboo scaoldings
Seismic retrot of exible steel frames using thin inll panels
Cracking analysis of rc members using polynomial strain distribution function
Experimental studies on shear lag of box girders
Numerical analysis of dynamic stability under random excitation
Green's functions for 2.5d elastodynamic problems in a free solid layer formation
31(4) 2002
Singh MP. Singh S. Moreschi LM.
Hwang JS. Wu JD. Pan TC. Yang G.
Katafygiotis LS. Lam HF.
Abbas AM. Manohar CS.
Doherty K. GriÆth MC. Lam N. Wilson J.
Koutsourelakis S. Prevost JH. Deodatis G.
Wang AP. Lee CD.
Li CX.
Yang JN. Lin S. Kim JH. Agrawal AK.
Mazars J. Kotronis P. Davenne L.
Singh MP. Moreschi LM.
Shum KM. Xu YL.
Wang JJ. Fan LC. Qian S. Zhou J.
Yuen KV. Beck JL. Katafygiotis LS.
Mylonakis G. Syngros C.
Malhotra PK.
Yalla SK. Kareem A.
24(4) 2002
Smith ST. Teng JG.
Smith ST. Teng JG.
Qiu FW. Li WF. Pan P. Qian JR.
Chung KF. Yu WK.
Bruneau M. Bhagwagar T.
Kwak HG. Song JY.
Luo QZ. Wu YM. Tang J. Li QS.
Williamson EB. Rungamornrat J.
Tadeu A. Antonio J.
501
517
Damage assessment in reinforced concrete beams using eigenfrequencies and mode
shape derivatives
Seismic response control of large-span machinery building on top of ship lift towers
using er/mr moment controllers
Ndambi JM. Vantomme J. Harri K.
Qu WL. Xu YL. Lv MY.
European Journal of Mechanics A-Solids
1
13
49
61
73
85
105
121
133
151
167
A comparison between the perzyna viscoplastic model and the consistency viscoplastic model
Boundary layers in thin elastic shells with developable middle surface
A variational inequality-based formulation of the frictional contact law with a
non-associated sliding rule
Strength or toughness? a criterion for crack onset at a notch
A shrink-t shaft subject to torsion
Thermodynamics and continuum fracture mechanics for nonlocal-elastic plastic
materials
Dynamic fragmentation of brittle solids: a multi-scale model
Uniaxial compressive failure of brittle materials as instability of damaging microcracked solids
Novel viscoelastic models for elastomers under nite strains
Instability analysis of vibrations of a uniformly moving mass in one and twodimensional elastic systems
Dynamic modelling of the double wishbone motor-vehicle suspension system
21(1) 2002
Heeres OM. Suiker ASJ. de Borst R.
Karamian P. Sanchez-Hubert J.
Hjiaj M. de Saxce G. Mroz Z.
Leguillon D.
Sackeld A. Barber JR. Hills DA. Truman CE.
Polizzotto C.
Denoual C. Hild F.
Gambarotta L. Monetto E.
Dimitrienko YI.
Kononov AV. de Borst R.
Attia HA.
Experimental Mechanics
1
Flexural fatigue behavior of threaded connections for large diameter pipes
8
A tension split hopkinson bar for investigating the dynamic behavior of sheet
metals
Application of the fourier transform in electronic speckle photography
Multiple force identication for complex structures
Circumferential strain measurement for a concrete cylinder in uniaxial compression by a ber optic sensor
The use of phase-stepping for the measurement of characteristic parameters in
integrated photoelasticity
A new microtensile tester for the study of mems materials with the aid of atomic
force microscopy
A shear-compression specimen for large strain testing
High-strain-rate compressive behavior of a rigid polyurethane foam with various
densities
A parametric study of laser induced thin lm spallation
Fabric thickness dynamic measurement during a classic uniaxial tensile test
Pulse shaping techniques for testing brittle materials with a split hopkinson pressure bar
Heating during shearing and opening dominated dynamic fracture of polymers
Novel load cell for measuring axial force, shear force, and bending movement in
large-scale structural experiments
In-situ tensile testing of nano-scale specimens in sem and tem
18
25
37
43
51
58
65
74
84
93
107
115
123
Experiments in Fluids
1
3
37
44
55
Retirement of wolfgang merzkirch
Velocity prole characterization in sub-millimeter diameter tubes using molecular
tagging velocimetry
Plane jets impinging on porous walls
Forces, moment and wave pattern for surface combatant in regular head waves
part ii. measurement results and discussion
Multiple hot-lm sensor array calibration and skin friction measurement
Control of backward-facing step ow using a apping foil
Accurate measurement of hydrodynamic interactions between a particle and walls
66
Experimental study of the synthesis of fused silica by direct combustion hydrolysis
16
27
11
42(1) 2002
Varma AH. Salecha AK. Wallace B. Russell
BW.
Huh H. Kang WJ. Han SS.
Zhang YP. Zhu HN. Zhou WL. Liu HF.
Adams R. Doyle JF.
Li QB. Ansari F.
Tomlinson RA. Patterson EA.
Chasiotis I. Knauss WG.
Rittel D. Lee S. Ravichandran G.
Chen W. Lu F. Winfree N.
Wang JL. Weaver RL. Sottos NR.
Fontaine S. Durand B. Freyburger JM.
Frew DJ. Forrestal MJ. Chen W.
Bjerke T. Lambros J.
Blakeborough A. Clement D. Williams MS.
Woodward N.
Haque MA. Saif MTA.
32(1) 2002
Gharib M. Rockwell D. Taylor A.
Maynes D. Webb AR.
Cant R. Castro I. Walklate P.
Gui L. Longo J. Metcalf B. Shao J. Stern F.
Desgeorges O. Lee T. Kafyeke F.
Lai JCS. Yue J. Platzer MF.
Masmoudi K. Lecoq N. Anthore R. Bostel F.
Feuillebois F.
Linow S. Schneider C. Geiss S. Janicka J. Hassel EP. Rudiger F.
12
76
87
99
106
116
121
136
Coherent structure identication from wavelet analysis of particle image velocimetry data
A kilohertz frame rate cinemagraphic piv system for laboratory-scale turbulent
and unsteady ows
Eects of gurney aps on the lift enhancement of a cropped nonslender delta wing
Performance of digital image velocimetry processing techniques
A three-dimensional photographic method for measurement of phase distribution
in dilute bubble ow
Voronoi imaging methods for the measurement of granular ows
Further characterization of large-scale coherent structure signatures in a
turbulent-plane mixing layer
Camussi R.
Upatnieks A. Laberteaux K. Ceccio SL.
Li YC. Wang JJ. Tan GK. Zhang PF.
McKenna SP. McGillis WR.
Luo R. Song Q. Yang XY. Wang Z.
Capart H. Young DL. Zech Y.
Auburn S. Boisson HC. Bonnet JP.
Fatigue & Fracture of Engineering Materials & Structures
99
Fatigue life recovery in aluminium alloy aircraft structure
111
127
141
Initiation and early growth of fatigue cracks in an aerospace aluminium alloy
Closure of plane-strain cracks under large-scale yielding conditions
In situ investigation of small fatigue crack growth in poly-crystal and singlecrystal aluminium alloys
Shape optimization of critical stiener runouts for f-111 airframe life extension
151
173
187
201
215
223
231
Adhesively bonded joints under cyclic loading spectra
Self-similar crack patterns induced by spatial stress uctuations
Plastically elastically dominant fatigue interaction in 316l stainless steel and 6061t6 aluminium alloy
Features of fatigue crack growth due to repeated thermal shock
The eect of solution heat-treatment time on the fatigue properties of an al-si-mg
casting alloy
A perturbation solution for a crack in a power-law material under gross yielding
25(2) 2002
Sharp PK. Liu Q. Barter SA. Baburamani P.
Clark G.
Barter SA. Sharp PK. Holden G. Clark G.
Wang CH. Rose LRF. Newman JC.
Zhang XP. Wang CH. Ye L. Mai YW.
Heller M. McDonald M. Burchill M. Watters
KC.
Jones R. Kotousov A. Marshall IH.
Dyskin AV.
Wong YK. Hu XZ. Norton MP.
Kerezsi BB. Price JWH. Kotousov AG.
Davidson CJ. GriÆths JR. Machin AS.
Chen GX. Wang CH. Rose LRF.
Flow, Turbulence & Combustion
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Using a fuzzy piecewise regression analysis to predict the nonlinear time-series of
turbulent ows with automatic change-point detection
Particle/turbulence interactions, mass transfer and gas/solid chemistry in a cfbc
riser
Extended proper orthogonal decomposition: application to jet/vortex interaction
Analysis of streamwise velocity uctuations in turbulent pipe ow with the use
of an ultrasonic doppler owmeter
On modelling periodic motion with turbulence closures
67(2) 2001
Tseng YH. Durbin P. Tzeng GH.
Zevenhoven R. Jarvinen M.
Maurel S. Boree J. Lumley JL.
Alfonsi G.
Cotton MA. Craft TJ. Guy AW. Launder BE.
IMA Journal of Applied Mathematics
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23
On the far-eld operator in elastic obstacle scattering
Mathematical analysis of the optimal location of wastewater outfalls
41
Mathematical modelling for keyhole surgery simulations: a biomechanical model
for spleen tissue
Asymptotic simplication for a reaction-diusion problem with a nonlinear
boundary condition
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67(1) 2002
Alves CJS. Kress R.
Alvarez-Vazquez LJ. Martinez A. Rodriguez
C. Vazquez-Mendez ME.
Davies PJ. Carter FJ. Cuschieri A.
de Pablo A. Quiros F. Rossi JD.
International Journal for Numerical & Analytical Methods
in Geomechanics
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121
139
163
181
Computational mechanics of the steel-concrete interface
A visco-plastic constitutive model for granular soils modied according to nonlocal and gradient approaches
Numerical solution for consolidation and desiccation of soft soils
EÆcient conditional modeling for geotechnical uncertainty evaluation
Upper bound limit analysis using linear nite elements and non-linear programming
26(2) 2002
Ben Romdhane MR. Ulm FJ.
di Prisco C. Imposimato S. Aifantis EC.
Yao DTC. de Oliveira WL. Cai XC. Znidarcic
D.
Graettinger AJ. Lee J. Reeves HW.
Lyamin AV. Sloan SW.
13
International Journal for Numerical & Analytical Methods
in Geomechanics
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231
259
273
299
Three-dimensional nite element analysis of the interaction between tunneling
and pile foundations
Explicit solutions for the instantaneous undrained contraction of hollow cylinders
and spheres in porous elastoplastic medium
Integration and calibration of a plasticity model for granular materials
Image-based modelling and analysis of microstructures for two-scale problems in
geomechanics
Fundamental solutions for a uid-saturated, transversely isotropic, poroelastic
solid
Mroueh H. Shahrour I.
Giraud A. Homand F. Labiouse V.
Jacobsson L. Runesson K.
Terada K. Kyoya T. Kazama M. Lee K. Oyang
L.
Taguchi I. Kurashige M.
International Journal for Numerical Methods in Engineering
1259
1277
1301
1323
1337
1353
1377
1393
1415
1433
1461
1477
1491
Computational micro-mechanical model of exible woven fabric for nite element
impact simulation
An interactive geometry utility environment for multi-disciplinary computational
engineering
Adaptive backward euler time stepping with truncation error control for numerical modelling of unsaturated uid ow
Convergence analysis of a hierarchical enrichment of dirichlet boundary conditions
in a mesh-free method
Tetrahedral composite nite elements
Higher-order responses of three-dimensional elastic plate structures and their numerical illustration by p-fem
Tetrahedral mesh improvement via optimization of the element condition number
An energy and momentum conserving method for rigid-exible body dynamics
A ux-limited numerical method for solving the mhd equations to simulate
propulsive plasma ows
Multifrontal incomplete factorization for indenite and complex symmetric systems
Three-dimensional nite element calculations in acoustic scattering using arbitrarily shaped convex articial boundaries
On non-linear behaviour of spherical shallow shells bonded with piezoelectric
actuators by the dierential quadrature element method (dqem)
A canonical form return mapping algorithm for rate independent plasticity
1533
1557
1575
1593
1615
1629
1641
1675
1695
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1751
An adaptive-recursive staggering strategy for simulating multield coupled processes in microheterogeneous solids
Thermo-elasto-plastic nite element analysis of quasi-state processes in eulerian
reference frames
On congurational forces in the context of the nite element method
Hat interpolation wavelet-based multi-scale galerkin method for thin-walled box
beam analysis
A new numerical method for the boundary optimal control problems of the heat
conduction equation
Comparison of method of lines and nite dierence solutions of 2-d navier-stokes
equations for transient laminar pipe ow
Stress analysis of gear teeth using displacement potential function and nite differences
A ga-based technique for layout optimization of truss with stress and displacement
constraints
A one-dimensional theory of thin-walled curved rectangular box beams under
torsion and out-of-plane bending
Analytical integrations in 2d bem elasticity
Development of shear locking-free shell elements using an enhanced assumed
strain formulation
Non-singular boundary integral formulations for plane interior potential problems
53(6) 2002
Tabiei A. Ivanov I.
Zheng Y. Weatherill NP. Turner-Smith EA.
Kavetski D. Binning P. Sloan SW.
Han WM. Wagner GJ. Liu WK.
Thoutireddy P. Molinari JF. Repetto EA. Ortiz M.
Dauge M. Rossle A. Yosibash Z.
Freitag LA. Knupp PM.
Puso MA.
Sankaran K. Martinelli L. Jardin SC. Choueiri
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Qu Y. Fish J.
Tezaur R. Macedo A. Farhat C. Djellouli R.
Wang XW. Wang YL.
Keavey MA.
International Journal for Numerical Methods in Engineering
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26(3) 2002
53(7) 2002
Zohdi TI.
Shanghvi JY. Michaleris P.
Mueller R. Kolling S. Gross D.
Kim YY. Jang GW.
Park HM. Lee WJ.
Selcuk N. Tarhan T. Tanrikulu S.
Akanda MAS. Ahmed SR. Uddin MW.
Azid IA. Kwan ASK. Seetharamu KN.
Kim YY. Kim Y.
Salvadori A.
de Sa JMAC. Jorge RMN. Valente RAF.
Areias PMA.
Hwang WS. Hung LP. Ko CH.
14
International Journal for Numerical Methods in Engineering
1765
1781
1801
1831
A nite point method for compressible ow
A new class of c-n interpolations and its application to the nite element method
Time-discretized variational formulation of non-smooth frictional contact
Arbitrary lagrangian-eulerian (ale) formulation for hyperelastoplasticity
1853
1871
An implicit bem formulation for gradient plasticity and localization phenomena
Hierarchical model adaptivity in nite element analysis for non-linear plate problems
Finite element evaluation of mixed mode stress intensity factors in functionally
graded materials
Moving particle nite element method
The extended nite element method (xfem) for solidication problems
Design space optimization using a numerical design continuation method
Three-dimensional nite element solution of gas-assisted injection moulding
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53(8) 2002
Lohner R. Sacco C. Onate E. Idelsohn S.
Hashemolhosseini H. Sadati N. Farzin M.
Pandol A. Kane C. Marsden JE. Ortiz M.
Rodriguez-Ferran A. Perez-Foguet A. Huerta
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Benallal A. Fudoli CA. Venturini WS.
Fu K.
Kim JH. Paulino GH.
Hao S. Park HS. Liu WK.
Chessa J. Smolinski P. Belytschko T.
Kim YI. Kwak BM.
Ilinca F. Hetu JF.
International Journal for Numerical Methods in Engineering
2019
2043
2061
2087
2117
2143
2163
2185
2201
2217
2239
2253
Contact between 3d beams with rectangular cross-sections
Second-order optimal control algorithm for complex systems
Mixed-enhanced formulation for geometrically linear axisymmetric problems
Meshfree analysis and design sensitivity analysis for shell structures
A simple algorithm for localized construction of non-matching structural interfaces
Low-frequency assessment of the in situ acoustic absorption of materials in rooms:
an inverse problem approach using evolutionary optimization
A stream function implicit nite dierence scheme for 2d incompressible ows of
newtonian uids
Hybrid time domain solvers for the maxwell equations in 2d
Development of a simple and eÆcient method for robust optimization
Implementation of cyclic plasticity models based on a general form of kinematic
hardening
Studies of multi-start clustering for global optimization
An approach to multi-start clustering for global optimization with non-linear
constraints
Litewka P. Wriggers P.
Kaplan ML. Heegaard JH.
Kasper EP. Taylor RL.
Kim NH. Choi KK. Chen JS. Botkin ME.
Park KC. Felippa CA. Rebel G.
Dutilleux G. Sgard FC. Kristiansen UR.
Bubnovich VI. Rosas CE. Moraga NO.
Abenius E. Andersson U. Edelvik F. Eriksson
L. Ledfelt G.
Jung DH. Lee BC.
Kobayashi M. Ohno N.
Tu W. Mayne RW.
Tu W. Mayne RW.
International Journal for Numerical Methods in Engineering
2271
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2311
2329
2357
2389
2413
Conservation properties of a time fe method - part iii: mechanical systems with
holonomic constraints
Speeding up the solution of thermal ehl problems
A simplied approach for incorporating thickness stress in the analysis of sheet
metal forming using shell elements
A posteriori error estimation in non-linear fe analyses of shell structures
Constitutive modeling of cementitious materials in the framework of chemoplasticity
An optimal high-order non-reecting nite element scheme for wave scattering
problems
Singularities in anisotropic steady-state heat conduction using a boundary element method
2445
2463
Optimum design of stochastically excited non-linear dynamic systems without
geometric constraints
A plasticity based model and an adaptive algorithm for nite element analysis of
reinforced concrete panels
Remeshing for metal forming simulations - part 1: two-dimensional quadrilateral
remeshing
53(10) 2002
Betsch P. Steinmann P.
Ford JM. Chen K.
Cho JW. Yang DY. Chung WJ.
Lackner R. Mang HA.
Lackner R. Hellmich C. Mang HA.
Givoli D. Patlashenko I.
Mera NS. Elliott L. Ingham DB. Lesnic D.
International Journal for Numerical Methods in Engineering
2429
53(9) 2002
53(11) 2002
Oblak MM. Lesnika AS. Butinar BJ.
Pravida J. Wunderlich W.
Kwak DY. Cheon JS. Im YT.
2501
2529
2549
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Remeshing for metal forming simulations - part ii: three-dimensional hexahedral
mesh generation
A 3d brick element based on hu-washizu variational principle for mesh distortion
Non-planar 3d crack growth by the extended nite element and level sets - part
i: mechanical model
Non-planar 3d crack growth by the extended nite element and level sets - part
ii: level set update
Cao YP. Hu N. Lu J. Fukunaga H. Yao ZH.
Moes N. Gravouil A. Belytschko T.
Gravouil A. Moes N. Belytschko T.
International Journal for Numerical Methods in Engineering
2587
2617
2643
2673
2701
2721
Non-linear version of stabilized conforming nodal integration for galerkin meshfree methods
Hybrid-stress solid elements for shell structures based upon a modied variational
functional
A control volume capacitance method for solidication modelling with mass transport
Automatic generation of anisotropic quadrilateral meshes on three-dimensional
surfaces using metric specications
Implicit stress integration procedure for small and large strains of the gurson
material model
Reconstructing dynamic events from time-limited spatially distributed data
447
471
Gas-assisted uid displacement in a circular tube and a rectangular channel
EÆcient computation of natural convection in a concentric annulus between an
outer square cylinder and an inner circular cylinder
Identication of regions of fastest mixing in a system of point vortices
Stability of explicit advection schemes. the balance point location rule
Sze KY. Lo SH.
Davey K. Rodriguez NJ.
Lee YK. Lee CK.
Kojic M. Vlastelica I. Zivkovic M.
Doyle JF.
38(5) 2002
Kamisli F. Ryan ME.
Shu C. Zhu YD.
Ramachandran P. Rajan SC.
Leonard BP.
International Journal for Numerical Methods in Fluids
515
533
555
567
589
A reappraisal of taylor-galerkin algorithm for drying-wetting areas in shallow
water computations
Numerical solution of the ow of thin viscous sheets under gravity and the inverse
windscreen sagging problem
Three dimensional tide-induced circulation model on a triangular mesh
An unconditionally stable, explicit godunov scheme for systems of conservation
laws
A simple and eÆcient error analysis for multi-step solution of the navier-stokes
equations
38(6) 2002
Quecedo M. Pastor M.
Hunt R.
Jiang WS. Sun WX.
Guinot V.
Fithen RM.
International Journal for Numerical Methods in Fluids
609
625
647
677
Application of local grid renement to vortex motion due to a solitary wave
passing over a submerged body
Improved linear interpolation practice for nite-volume schemes on complex grids
Iterative explicit simulation of 1d surges and dam-break ows
Simulation of pressure-tooling wire-coating ow with phan-thien/tanner models
International Journal for Numerical Methods in Fluids
711
729
747
769
789
A three-dimensional boundary layer scheme: stability and accuracy analyses
Selection of a staggered grid for inertia-gravity waves in shallow water
Finite volume scheme for the solution of uid ow problems on unstructured
non-staggered grids
Numerical solutions of the shallow water equations with discontinuous bed topography
Numerical solution of incompressible ows by discrete singular convolution
53(12) 2002
Chen JS. Yoon SP. Wu CT.
International Journal for Numerical Methods in Fluids
407
429
15
Kwak DY. Im YT.
38(7) 2002
Tang CJ. Chang JH.
Lehnhauser T. Schafer M.
Hsu CT. Yeh KC.
Ngamaramvaranggul V. Webster MF.
38(8) 2002
Horri-Naceur J. Buisine D.
Beckers JM.
Barton IE. Markham-Smith D. Bresslo N.
Zhou JG. Causon DM. Ingram DM. Mingham
CG.
Wan DC. Zhou YC. Wei GW.
16
International Journal for Numerical Methods in Fluids
811
849
861
881
895
A low-dimensional spectral approach for the nonlinear overstability of purely
elastic uids
Parallel solution of a coupled ow and transport model for shallow water
A low-dimensional spectral approach for transient axisymmetric free-surface ow
inside thin cavities of arbitrary shape
On the use of the galerkin method for 3d numerical modelling of the general
circulation: the south atlantic experiment
The eect of solutal undercooling on double-diusive convection and macrosegregation during binary alloy solidication: a numerical investigation
38(9) 2002
Khayat RE.
Sommeijer BP. van der Houwen PJ.
Khayat RE. Simanowski A.
Harari J. Giarolla E.
Chakraborty S. Dutta P.
International Journal of Engineering Science
347
367
385
401
411
433
449
461
Stress analysis of a bonded repair over a corrosion grind-out using an inclusion
model with a second ordered eigenstrain theory
Stochastic equations of rigid-thermo-viscoplasticity in metal forming process
Growth and decay in generalized thermoelasticity
Contact problem for porous elastic strip
Unsteady ow and heat transfer of a viscous uid in the stagnation region of a
three-dimensional body with a magnetic eld
Fourth-order techniques for identifying a control parameter in the parabolic equations
Rayleigh-benard convection in a micropolar ferromagnetic uid
Description of magneto rheological behavior with internal variables
40(4) 2002
Duong CN. Yu J.
Grzywinski M. Sluzalec A.
Payne LE. Song JC.
Scalia A.
Kumari M. Nath G.
Dehghan M.
Abraham A.
Chen KC. Yeh CS.
International Journal of Engineering Science
485
499
511
531
549
569
587
On the spatial behaviour of the transient and steady-state solutions in thin plates
with transverse shear deformation
A method to model simple tension experiments using nite elasticity theory with
an application to some polyurethane foams
A poroelastic bone model for internal remodeling
Non-similarity solution and correlation of transient heat transfer in laminar
boundary layer ow over a wedge
On the micromorphic thermoelasticity
Evaluation of the stress eld around a notch tip using contour integrals
A two-dimensional problem for a half-space in magneto-thermoelasticity with
thermal relaxation
40(5) 2002
Ciarletta M.
Murphy JG. Rogerson GA.
Papathanasopoulou VA. Fotiadis DI. Foutsitzi
G. Massalas CV.
Cheng WT. Lin HT.
Iesan D.
Chang JH. Kang LK.
Sherief HH. Helmy KA.
International Journal of Fracture
107
125
153
175
Finite volume analysis of dynamic fracture phenomena - i. a node release methodology
Finite volume analysis of dynamic fracture phenomena - ii. a cohesive zone type
methodology
Crack-tip constraint in mode ii deformation
Prediction of shear crack growth direction under compressive loading and plane
strain conditions
113(2) 2002
Stylianou V. Ivankovic A.
Stylianou V. Ivankovic A.
Ayatollahi MR. Smith DJ. Pavier MJ.
Isaksson P. Stahle P.
International Journal of Fracture
195
213
233
253
267
285
Eects of mode mix upon fracture behavior of a solder joint
Afm and sem observation on mechanism of fatigue crack growth in an fe-si single
crystal
Thin layer splitting along the elastic-plastic solid surface
Fractal characteristics of composite pipes defects in torsion testing
Dual boundary element method for axisymmetric crack analysis
Determination of stress intensity factors for bimaterial interface stationary rigid
line inclusions by boundary element method
113(3) 2002
Kang KJ. Kim DH. Choi SH.
Oda Y. Furuya Y. Noguchi H. Higashida K.
Wei YG.
Cetera A. Blazejewski W.
de Lacerda LA. Wrobel LC.
Lee KY. Kwak SG.
17
International Journal of Fracture
295
309
327
345
367
A new look at energy release rate in fracture mechanics
Crack-tip elds in anisotropic shells
The fracture behaviour of intermetallic tial alloys with and without warm prestressing
Report on onr workshop on fracture scaling
Viscoelastic crack growth process in wood timbers: an approach by the nite
element method for mode i fracture
113(4) 2002
Sun CT. Wang CY.
Yuan FG. Yang S.
Chen JH. Pippan R. Hebesberger T. Kolednik
O.
Bazant ZP. Rajapakse YDS. Allen DH. Ballarini R. Espinosa HD. Gao H. Gettu R. Jirasek
M. Pijaudier-Cabot G. Planas J. Ulm FJ.
Dubois F. Chazal C. Petit C.
International Journal of Heat & Fluid Flow
107
109
137
Preface
Heat transfer research on gas turbine airfoils at nasa grc
Elevated freestream turbulence eects on heat transfer for a gas turbine vane
148
Progress in the generalization of wall-function treatments
161
Scalar dispersion from an instantaneous line source at the wall of a turbulent
channel for medium and high prandtl number uids
Turbulent heat transfer from a multi-layered wall-mounted cube matrix: a large
eddy simulation
Heat transfer in transitional and turbulent boundary layers with system rotation
Heat transfer enhancement by gortler instability
Investigation of the ow eld of a highly heated jet of air
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23(2) 2002
Ball KS. Schmidt FW.
Garg VK.
Thole KA. Radomsky RW. Kang MB. Kohli
A.
Craft TJ. Gerasimov AV. Iacovides H. Launder
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Papavassiliou DV.
Niceno B. Dronkers ADT. Hanjalic K.
Yamawaki D. Obi S. Masuda S.
Toe R. Ajakh A. Peerhossaini H.
Anderson SM. Bremhorst K.
International Journal of Heat & Mass Transfer
1789
Congratulations to prof. erich hahne, on the occasion of his 70th birthday
1791
Subcooled ow boiling heat transfer of r-134a and the associated bubble characteristics in a vertical plate heat exchanger
Second law analysis of a waste heat recovery steam generator
Convective heat transfer of exothermic reactive gas owing across a heating cylinder coated with platinum catalyst in a narrow duct
Flow and heat transfer in rotating two-pass rectangular channels (ar=2) by
reynolds stress turbulence model
Measurement of apparent solid-side mass diusivity of a water vapor-silica gel
system
Computational modeling for honeycomb-stator gas annular seal
Temperature solution in multi-dimensional multi-layer bodies
Eects of radius and heat transfer on the prole of evaporating thin liquid lm
and meniscus in capillary tubes
Energy analysis of evaporating thin falling lm instability in vertical tube
Analytical solutions of 1-d heat conduction problem for a single n with temperature dependent heat transfer coeÆcient - i. closed-form inverse solution
Analytical solutions of the 1-d heat conduction problem for a single n with
temperature dependent heat transfer coeÆcient - ii. recurrent direct solution
1807
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45(9) 2002
Muller-Steinhagen H. Minkowycz WJ. Hartnett JP. Rose JW.
Hsieh YY. Chiang LJ. Lin TF.
Reddy BV. Ramkiran G. Kumar KA. Nag PK.
Itaya Y. Hiroi T. Matsuda H. Hasatani M.
Al-Qahtani M. Jang YJ. Chen HC. Han JC.
Ni CC. San JY.
Chochua G. Shyy W. Moore J.
Haji-Sheikh A. Beck JV.
Qu W. Ma TZ. Miao JY. Wang JL.
Du XZ. Wang BX. Wu SR. Jiang SY.
Dul'kin IN. Garas'ko GI.
Dul'kin IN. Garas'ko GI.
International Journal of Plasticity
281
313
345
359
Reactive plasticity for clays during dehydration and rehydration. part 1: concepts
and options
A non-linear analysis of non-isothermal wave propagation in linear-elastic uidsaturated porous media
Steady crack growth in elastic-plastic uid-saturated porous media
Comparison of two grain interaction models for polycrystal plasticity and deformation texture prediction
18(3) 2002
Hueckel T.
Gajo A.
Radi E. Bigoni D. Loret B.
Van Houtte P. Delannay L. Kalidindi SR.
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379
399
415
Energy balance and identication of hardening moduli in plastic deformation
processes
Application of a large deformation model to unstable tensile stretching of
polyethylene
Damage and size eect during superplastic deformation
Mroz Z. Oliferuk W.
Sweeney J. Collins TLD. Coates PD. Unwin
AP. Duckett RA. Ward IM.
Taylor MB. Zbib HM. Khaleel MA.
Inverse Problems in Engineering
431
Electrical process tomography with known internal structures and resistivities
455
Local spline-approximation method of solving some coeÆcient inverse problems
for dierential equation of the parabolic type
Numerical solution of a rst kind integral equation of potential theory
Developing nuclear magnetic resonance imaging for engineering applications
Estimation of thermophysical properties of composites using multi-parameter estimation and zeroth-order regularization
Multi-dimensional heat ux reconstruction using narrow-band thermochromic liquid crystal thermography
State space models in process tomography - approximation of state noise covariance
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561
9(5) 2001
Heikkinen LM. Vauhkonen M. Savolainen T.
Leinonen K. Kaipio JP.
Grebennikov A.
Flores JD.
Watson AT. Hollenshead JT. Chang CTP.
Aviles-Ramos C. Haji-Sheikh A.
Kassab AJ. Divo E. Kapat JS.
Seppanen A. Vauhkonen M. Somersalo E. Kaipio JP.
Inverse Problems in Engineering
587
619
645
671
Absorption coeÆcient estimation in heterogeneous media using a domain partition consistent with divergent beams
Boundary inverse heat conduction problem: algorithm and error analysis
Parametric identication of viscoelastic materials from time and frequency domain data
Stochastic regularization of feedwater ow rate evaluation for the venturi meter
fouling problem in nuclear power plants
9(6) 2001
Montero RFC. Roberty NC. Neto AJS.
Alifanov OM. Nenarokomov AV.
Mossberg M. Hillstrom L. Abrahamsson L.
Gribok AV. Attieh IK. Hines JW. Uhrig RE.
Journal of Composite Materials
3
19
47
69
93
Nonlinear viscoelastic nite element analyses of thermosetting polymeric composites during cool-down after curing
Cure cycle for thick glass/epoxy composite laminates
The response of composite joints with bolt-clamping loads, part 1: model development
The response of composite joints with bolt-clamping loads, part ii: model verication
Stress and failure analysis of 3d angle interlock woven composites
36(1) 2002
Yi S. Chian KS. Hilton HH.
Oh JH. Lee DG.
Sun HT. Chang FK. Qing XL.
Sun HT. Chang FK. Qing XL.
Naik NK. Azad SNM. Prasad PD.
Journal of Computational Physics
363
398
412
438
454
487
525
559
576
584
604
645
674
702
Separable and nonseparable multiwavelets in multiple dimensions
Evaluation of the modied bessel function of the third kind of imaginary orders
Bounded skew high-order resolution schemes for the discrete ordinates method
Algebraic splitting for incompressible navier-stokes equations
High-order monotonicity-preserving compact schemes for linear scalar advection
on 2-d irregular meshes
On time-splitting spectral approximations for the schrodinger equation in the
semiclassical regime
Flux correction tools for nite elements
Semi-lagrangian schemes for hamilton-jacobi equations, discrete representation
formulae and godunov methods
Calculation of the quantum entanglement measure of bipartite states, based on
relative entropy, using genetic algorithms
Construction of commutative lters for les on unstructured meshes
Motion of curves constrained on surfaces using a level-set approach
Hyperbolic divergence cleaning for the mhd equations
Hybrid ux-splitting schemes for a two-phase ow model
A comparison of spectral and vortex methods in three-dimensional incompressible
ows
175(2) 2002
Tymczak CJ. Niklasson AMN. Roder H.
Gil A. Segura J. Temme NM.
Coelho PJ.
Henriksen MO. Holmen J.
Tran QH. Scheurer B.
Bao WZ. Jin S. Markowich PA.
Kuzmin D. Turek S.
Falcone M. Ferretti R.
Ramos RV. Souza RF.
Marsden AL. Vasilyev OV. Moin P.
Cheng LT. Burchard P. Merriman B. Osher S.
Dedner A. Kemm F. Kroner D. Munz CD.
Schnitzer T. Wesenberg M.
Evje S. Fjelde KK.
Cottet GH. Michaux B. Ossia S. VanderLinden
G.
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739
764
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Numerical simulation of isotropic turbulence using a collocated approach and a
nonorthogonal grid system
An explicit fourth-order orthogonal curvilinear staggered-grid fdtd method for
maxwell's equations
Accuracy and conservation properties of a three-dimensional unstructured staggered mesh scheme for uid dynamics
Exactly conservative semi-lagrangian scheme for multi-dimensional hyperbolic
equations with directional splitting technique (vol 174, pg 171, 2001)
Xie ZQ. Chan CH. Zhang B.
Zhang X. Schmidt D. Perot B.
Nakamura T. Tanaka R. Yabe T. Takizawa K.
Journal of Computational Physics
1
20
40
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129
145
170
196
205
EÆcient and rapid numerical evaluation of the two-electron, four-center coulomb
integrals using nonlinear transformations and useful properties of sine and bessel
functions
A nonlinear ux split method for hyperbolic conservation laws
Grid adaptation for functional outputs: application to two-dimensional inviscid
ows
2d simulation of a silicon mesfet with a nonparabolic hydrodynamical model based
on the maximum entropy principle
Reference jacobian optimization-based rezone strategies for arbitrary lagrangian
eulerian methods
Numerical analysis of dusty-gas ows
C-innity-interpolation of discrete elds on regular and irregular grids
A numerical method for the solution of electromagnetic wave diraction problems
on perfectly conducting screens
Optimal annealing schedules for a modied tsallis statistics
A second-order-accurate symmetric discretization of the poisson equation on irregular domains
176(1) 2002
Safouhi H.
Stiriba Y.
Venditti DA. Darmofal DL.
Romano V.
Knupp P. Margolin LG. Shashkov M.
Saito T.
Giona M. Cerbelli S.
Kanaun SK.
Franz A. Homann KH.
Gibou F. Fedkiw RP. Cheng LT. Kang MJ.
Journal of Computational Physics
231
276
295
330
345
363
384
402
430
456
483
A cartesian grid method for solving the two-dimensional streamfunction-vorticity
equations in irregular regions
Dust dynamics in protoplanetary disks: parallel computing with pvm
Numerical study of quantum resonances in chaotic scattering
Consistent boundary conditions for multicomponent real gas mixtures based on
characteristic waves
A stable scheme for the numerical computation of long wave propagation in temporal laminates
A pressure-based method for turbulent cavitating ow computations
An eÆcient spectral-projection method for the navier-stokes equations in cylindrical geometries ii. three-dimensional cases
A numerical method to simulate radio-frequency plasma discharges
Exponential time dierencing for sti systems
Stress calculations on multiply connected domains
A parallelized meshfree method with boundary enrichment for large-scale cfd
176(2) 2002
Calhoun D.
Marcos CD. Barge P. Marcos RD.
Lin KK.
Okong'o N. Bellan J.
Weekes SL.
Senocak I. Shyy W.
Lopez JM. Marques F. Shen J.
Hammond EP. Mahesh K. Moin P.
Cox SM. Matthews PC.
Helsing J. Jonsson A.
Zhang LT. Wagner GJ. Liu WK.
Journal of Elasticity
87
113
137
153
Exponential stability to a contact problem of partially viscoelastic materials
A partially built-in plate under uniform load
A boussinesq-cerruti solution set for constant and linear distribution of normal
and tangential load over a triangular area
An exact theory for circular, end-loaded, anisotropic beams of narrow rectangular
cross section
63(2) 2001
Rivera JEM. Oquendo HP.
Gregory RD.
Li JS. Berger EJ.
Ladeveze P. Simmonds JG.
Journal of Elasticity
171
221
Asymptotic analysis of the eversion of nonlinearly elastic shells - ii. incompressible
shells
Implications and constraints of time-independent poisson ratios in linear isotropic
and anisotropic viscoelasticity
19
Lopes AS. Palma JMLM.
63(3) 2001
Antman SS. Srubshchik LS.
Hilton HH.
20
Journal of Engineering Mathematics
1
23
45
65
A numerical study of pulsatile blood ow in an eccentric catheterized artery using
a fast algorithm
Boundary-layer behaviour in a hydraulic theory of horizontal oil wells
Mass-transport enhancement in regions bounded by rigid walls
Acoustically generated unsteady vorticity eld in a long narrow cylinder with
sidewall injection
42(1) 2002
Daripa P. Dash RK.
Schulkes RMSM. King AC.
Trevelyan PMJ. Kalliadasis S. Merkin JH.
Scott SK.
Kirkkopru K. Kassoy DR. Zha Q. Staab PL.
Journal of Engineering Mechanics-ASCE
134
143
156
164
172
184
190
202
209
220
231
240
249
Response of 1/4-scale concrete masonry unit (cmu) walls to blast
Plane turbulent wall jets in shallow tailwater
Study of the behavior of concrete under triaxial compression
Wave diraction by a vertical cylinder with a porous ring plate
Use of microwaves for damage detection of ber reinforced polymer-wrapped concrete structures
Torsional surface waves in an initially stressed anisotropic porous medium
Polynomial chaos decomposition for the simulation of non-gaussian nonstationary
stochastic processes
Eective hybrid/mixed nite elements for folded-plate structures
Analytic solution for nite transversely isotropic circular cylinders under the axial
point load test
Formulation of cracked beam element for structural analysis
Element-free method based on lagrange polynomial
A boundary element analysis of quasi-brittle solids containing cracks
Similarity shapes of an inclined, partially lled membrane container
128(2) 2002
Dennis ST. Baylot JT. Woodson SC.
Ead SA. Rajaratnam N.
Sfer D. Carol I. Gettu R. Etse G.
Wu JH. Chwang AT.
Feng MQ. De Flaviis F. Kim YJ.
Dey S. Sarkar MG.
Sakamoto S. Ghanem R.
Duan M. Miyamoto Y.
Wei XX. Chau KT.
Viola E. Nobile L. Federici L.
Suetake Y.
Qin F. Cen ZZ. Fung TC.
Wang CY.
Journal of Engineering Mechanics-ASCE
254
264
280
287
296
308
318
328
340
351
359
369
371
376
377
Size eect on strength of oating sea ice under vertical line load
Study of passive deck-aps utter control system on full bridge model. i: theory
Study of passive deck-aps utter control system on full bridge model. ii: results
Protecting base-isolated structures from near-eld ground motion by tuned interaction damper
Postbuckling of shear deformable laminated cylindrical shells
Earthquake response and energy evaluation of inelastic structures
Spectral analysis and parametric study of stochastic pavement loads
Dynamics of nonviscously damped linear systems
Bayesian modal updating using complete input and incomplete response noisy
measurements
Reducing dispersion of linear triangular elements for the helmholtz equation
Time-harmonic analysis of wave propagation in unbounded layered strata with
zigzag boundaries
Addendum to "why did the world trade center collapse? - simple analysis"
Graphical relationship among lame ellipsoid and mohr's circles. a graphical view
of mohr's circles
Discussion of "structural damage detection from modal strain energy change" by
z. y. shi, s. s. law, and l. m. zhang
Closure to "structural damage detection from modal strain energy change" by z.
y. shi, s. s. law, and l. m. zhang
128(3) 2002
Bazant ZP. Guo ZY.
Omenzetter P. Wilde K. Fujino Y.
Omenzetter P. Wilde K. Fujino Y.
Zhang YF. Iwan WD.
Shen HS.
Wong KKF. Yang R.
Sun L. Kennedy TW.
Adhikari S.
Yuen KV. Katafygiotis LS.
Harari I. Nogueira CL.
Park SH. Tassoulas JL.
Bazant ZP. Zhou Y.
Montans FJ.
Ren WX. De Roeck G.
Shi ZY. Law SS. Zhang LM.
Journal of Fluid Mechanics
1
35
67
97
131
Numerical investigation of the interaction of the klebano-mode with a tollmienschlichting wave
The eects of heat release on the energy exchange in reacting turbulent shear
ow
The two-sided lid-driven cavity: experiments on stationary and time-dependent
ows
Experimental investigation of density uctuations in high-speed jets and correlation with generated noise
Stratied kolmogorov ow
450 2002
Fasel HF.
Livescu D. Jaberi FA. Madnia CK.
Blohm CH. Kuhlmann HC.
Panda J. Seasholtz RG.
Balmforth NJ. Young YN.
169
201
207
235
259
287
297
317
343
377
Start-up ows in a three-dimensional rectangular driven cavity of aspect ratio 1
: 1 : 2 at re=1000
Spatial versions of the zakharov and dysthe evolution equations for deep-water
gravity waves
Oscillating structures in a stretched-compressed vortex
Instability of an annular jet surrounded by a viscous gas in a pipe
Direct numerical simulation of turbulent channel ow with permeable walls
A new model for shallow water in the low-rossby-number limit
Convection in a spherical capacitor
Some observations of the eects of micro-organisms growing on the bed of an
open channel on the turbulence properties
Aerodynamic ow-vectoring of a planar jet in a co-owing stream
A study of the ow-eld evolution and mixing in a planar turbulent jet using
direct numerical simulation
21
Guermond JL. Migeon C. Pineau G. Quartapelle L.
Kit E. Shemer L.
Abid M. Andreotti B. Douad S. Nore C.
Chen JN. Lin SP.
Hahn S. Je J. Choi H.
Ford R. Malham SJA. Oliver M.
Amara K. Hegseth J.
Nikora VI. Goring DG. Biggs BJF.
Lim DW. Redekopp LG.
Stanley SA. Sarkar S. Mellado JP.
Journal of Fluid Mechanics
1
35
99
145
169
Bragg scattering of random surface gravity waves by irregular seabed topography
Subcritical transition in channel ows
Dependence of the non-stationary form of yaglom's equation on the schmidt number
A numerical investigation of solitary internal waves with trapped cores formed
via shoaling
Generation of slow large scales in forced rotating stratied turbulence
Fluidization of 1204 spheres: simulation and experiment
193
203
Wilton ripples generated by a moving pressure distribution
Sand bars in tidal channels part 2. tidal meanders
239
Density-driven unstable ows of miscible uids in a hele-shaw cell
261
Density-driven instabilities of miscible uids in a hele-shaw cell: linear stability
analysis of the three-dimensional stokes equations
Inclined turbulent fountains
Transient motion of a conned stratied uid induced simultaneously by sidewall
thermal loading and vertical throughow
Optimal perturbations in a four-vortex aircraft wake in counter-rotating conguration
A study of compressibility eects in the high-speed turbulent shear layer using
direct simulation
The ejecta sheet generated by the impact of a drop
The turbulent/non-turbulent interface bounding a far wake
Four-phase merging in sessile compound drops
Force on a body in a continuously stratied uid. part 1. circular cylinder
109
283
295
319
329
373
383
411
421
451 2002
Fabrice A. Herbers THC.
Chapman SJ.
Orlandi P. Antonia RA.
Lamb KG.
Smith LM. Walee F.
Pan TW. Joseph DD. Bai R. Glowinski R.
Sarin V.
Vanden-Broeck JM.
Solari L. Seminara G. Lanzoni S. Marani M.
Rinaldo A.
Fernandez J. Kurowski P. Petitjeans P.
Meiburg E.
Graf F. Meiburg E. Hartel C.
Bloomeld LJ. Kerr RC.
Park JS. Hyun JM.
Fabre D. Jacquin L. Loof A.
Pantano C. Sarkar S.
Thoroddsen ST.
Bisset DK. Hunt JCR. Rogers MM.
Mahadevan L. Adda-Bedia M. Pomeau Y.
Ermanyuk EV. Gavrilov NV.
Journal of Fluid Mechanics
1
25
39
61
97
123
145
163
189
199
231
263
293
303
325
Revisiting the 1954 suspension experiments of r. a. bagnold
Salt ngers at low rayleigh numbers
Probing structures in channel ow through so(3) and so(2) decomposition
Analysis of drag and virtual mass forces in bubbly suspensions using an implicit
formulation of the lattice boltzmann method
Stability of a buoyancy-driven coastal current at the shelf break
Stability of steep gravity-capillary solitary waves in deep water
Inertially driven inhomogeneities in violently collapsing bubbles: the validity of
the rayleigh-plesset equation
Electrohydrodynamic stability: taylor-melcher theory for a liquid bridge suspended in a dielectric gas
High-reynolds-number turbulence in small apparatus: grid turbulence in cryogenic liquids
Transport enhancement mechanisms in open cavities
Improvement of the stokesian dynamics method for systems with a nite number
of particles
A super-rotating shear layer in magnetohydrodynamic spherical couette ow
Shocks in sand owing in a silo
Instability of a bed of particles sheared by a viscous ow
The actively controlled jet in crossow
452 2002
Hunt ML. Zenit R. Campbell CS. Brennen CE.
Krishnamurti R. Jo YH. Stocchino A.
Biferale L. Lohse D. Mazzitelli IM. Toschi F.
Sankaranarayanan K. Shan X. Kevrekidis IG.
Sundaresan S.
Cenedese C. Linden PF.
Calvo DC. Akylas TR.
Lin H. Storey BD. Szeri AJ.
Burcham CL. Saville DA.
White CM. Karpetis AN. Sreenivasan KR.
Horner M. Metcalfe G. Wiggins S. Ottino JM.
Ichiki K.
Dormy E. Jault D. Soward AM.
Samadani A. Mahadevan L. Kudrolli A.
Charru F. Mouilleron-Arnould H.
M'Closkey RT. King JM. Cortelezzi L.
Karagozian AR.
22
337
361
371
405
425
On stationary solutions for free quasi-parallel mixing layers with a longitudinal
magnetic eld
Scaling of acceleration in locally isotropic turbulence
Constitutive laws in liquid-uidized beds
Gravitaxis in motile micro-organisms: the role of fore-aft body asymmetry
Shear stress of a monolayer of rough spheres
Journal of Fluid Mechanics
1
21
39
57
109
133
153
177
201
239
263
289
315
345
371
395
411
427
Using surfactants to control the formation and size of wakes behind moving bubbles at order-one reynolds numbers
Ferromagnetic rotating couette ow: the role of magnetic viscosity
Boundary layer development on a semi-innite suddenly heated vertical plate
Coherent structure generation in near-wall turbulence
Rayleigh-taylor instability of viscoelastic drops at high weber numbers
Friction law for dense granular ows: application to the motion of a mass down
a rough inclined plane
Long-wave instabilities of non-uniformly heated falling lms
Oblique transition in a laminar blasius boundary layer
Large-eddy simulation of the turbulent ow through a heated square duct
A study of three-dimensional gravity currents on a uniform slope
Spatial variations of a passive tracer in a random wave eld
Generation of sound and instability waves due to unsteady suction and injection
Moderate-reynolds-number ow in a wall-bounded porous medium
Rayleigh-benard convection in liquid metal layers under the inuence of a horizontal magnetic eld
The propagation of a gravity current into a linearly stratied uid
Velocity uctuations in a homogeneous dilute dispersion of high-reynolds-number
rising bubbles
Analytic solutions of the temperature distribution in blasius viscous ow problems
Coalescence of sessile drops
Journal of Fluid Mechanics
1
21
47
71
113
145
203
235
263
287
327
345
365
387
403
419
Modelling the morning glory of the gulf of carpentaria
Weakly stratied laminar ow past normal at plates
The onset of chaos in vortex sheet ow
Vertical structure in stratied wakes with high initial froude number
Experimental study of a jet in a crossow at very low reynolds number
Collision and rebound of small droplets in an incompressible continuum gas
The velocity eld under breaking waves: coherent structures and turbulence
A lubrication model of coating ows over a curved substrate in space
Slip velocity and lift
A vlasov equation for pressure wave propagation in bubbly uids
Uniform steady free-surface ow in heterogeneous porous formations
The motion generated by a rising particle in a rotating uid - numerical solutions.
part 2. the long container case
On converging shock waves of spherical and polyhedral form
Spectral solution of time-dependent shallow water hydroelasticity
Do true elevation gravity-capillary solitary waves exist? a numerical investigation
Stretching eects on the three-dimensional stability of vortices with axial ow
Journal of Fluids & Structures
123
137
153
175
Dynamics of an in-line tube array subjected to steam-water cross-ow. part i:
two-phase damping and added mass
Dynamics of an in-line tube array subjected to steam-water cross-ow. part i:
unsteady uid forces
Dynamics of an in-line tube array subjected to steam-water cross-ow. part iii:
uidelastic instability tests and comparison with theory
Flow visualization around a circular cylinder near to a plane wall
Shukhman IG.
Hill RJ.
Duru P. Nicolas M. Hinch J. Guazzelli E.
Roberts AM. Deacon FM.
Wilson HJ. Davis RH.
453 2002
Wang YP. Papageorgiou DT. Maldarelli C.
Hart JE.
Patterson JC. Graham T. Schopf W. Armeld
SW.
Schoppa W. Hussain F.
Joseph DD. Beavers GS. Funada T.
Pouliquen O. Forterre Y.
Miladinova S. Slavtchev S. Lebon G. Legros
JC.
King RA. Breuer KS.
Vazquez MS. Metais O.
Ross AN. Linden PF. Dalziel SB.
Weichman PB. Glazman RE.
Wu XS.
Hill RJ. Koch DL.
Burr U. Moller U.
Maxworthy T. Leilich J. Simpson JE. Meiburg
EH.
Risso F. Ellingsen K.
Liao SJ. Campo A.
Andrieu C. Beysens DA. Nikolayev VS.
Pomeau Y.
454 2002
Porter A. Smyth NF.
Castro IP.
Krasny R. Nitsche M.
Spedding GR.
Camussi R. Guj G. Stella A.
Gopinath A. Koch DL.
Melville WK. Veron F. White CJ.
Roy RV. Roberts AJ. Simpson ME.
Joseph DD. Ocando D.
Smereka P.
Amir O. Dagan G.
Minkov E. Ungarish M. Israeli M.
Schwendeman DW.
Meylan MH.
Champneys AR. Vanden-Broeck JM. Lord GJ.
Delbende I. Rossi M. Le Dizes S.
16(2) 2002
Nakamura T. Hirota K. Watanabe Y. Mureithi
NW. Kusakabe T. Takamatsu H.
Mureithi NW. Nakamura T. Hirota K. Murata
M. Utsumi S. Kusakabe T. Takamatsu H.
Hirota K. Nakamura T. Kasahara J. Mureithi
NW. Kusakabe T. Takamatsu H.
Price SJ. Sumner D. Smith JG. Leong K.
Paidoussis MP.
193
213
229
247
263
Dynamics of mooring cables in random seas
Experimental study on large-amplitude vibrations of water-lled circular cylindrical shells
Two-dimensional vortex-induced vibration of cable suspensions
Mechanism of mode selection for taylor vortex ow between coaxial conical rotating cylinders
Near-wake ow structure of a cylinder with a helical surface perturbation
Sarkar A. Taylor RE.
Amabili M. Garziera R. Negri A.
Kim WJ. Perkins NC.
Noui-Mehidi MN. Ohmura N. Kataoka K.
Chyu CK. Rockwell D.
Journal of Intelligent Material Systems & Structures
923
930
High bandwidth tunability in a smart vibration absorber
Rechargeable lithium batteries for powering piezoelectric devices
936
945
Vibration control of a mr seat damper for commercial vehicles
Smart uid damping: shaping the force/velocity response through feedback control
Characterization of piezoelectric wafer active sensors
Shape memory elements in bending: inuence of the shape of their cross-section
959
977
11(12) 2000
Flatau AB. Dapino MJ. Calkins FT.
Salloux K. Lim J. Dunn B. Chaplya PM. Carman GP.
Choi SB. Nam MH. Lee BK.
Sims ND. Stanway R. Johnson AR. Peel DJ.
Bullough WA.
Giurgiutiu V. Zagrai AN.
Kafka V. Vokoun D.
Journal of Intelligent Material Systems & Structures
3
11
41
Robust pole assignment for vibration control of exible structures
Limitations of using membrane theory for modeling pvdf patches on inatable
structures
Mechanism-based phenomenological models for the pseudoelastic hysteresis behavior of shape memory alloys
Eigenstrain techniques for modeling adaptive structures. i: active stiness tailoring
A continuous sensor to measure acoustic waves in plates
57
Electrorheological eects of er gels containing iron particles
21
31
12(1) 2001
Okubo H. Ichikawa H.
Williams RB. Austin EM. Inman DJ.
Malovrh B. Gandhi F.
Alghamdi AAA. Dasgupta A.
Sundaresan MJ. Ghoshal A. Martin WN.
Schulz MJ.
Liu B. Shaw MT.
Journal of Intelligent Material Systems & Structures
67
69
79
93
105
117
127
133
Special issue: third international conference on mechanics and materials in design
symposium on smart materials and adaptive structures - preface
A nite element analysis of second order eects on the frequency response of a
saw device
A micromechanics-based hysteresis model for ferroelectric ceramics
Control of transient thermoelastic displacement in a piezoelectric based intelligent
plate
Wave propagation in electromechanical structures: induced by surface-bonded
piezoelectric actuators
Wave propagation in electromechanical structures: induced by embedded piezoelectric actuators
Energy conversion in shape memory alloy heat engine - part i: theory
Energy conversion in shape memory alloy heat engine - part ii: simulation
12(2) 2001
Wang X.
Xu GS. Jiang Q.
Li J. Weng GJ.
Ashida F. Noda N.
Wang XD. Huang GL.
Wang XD. Huang GL.
Zhu JJ. Liang NG. Liew KM. Huang WM.
Zhu JJ. Liang NG. Huang WM. Liew KM.
Journal of Intelligent Material Systems & Structures
143
157
161
165
183
191
Feedback control of the bending response of ionic polymer actuators
Single axis piezoceramic gimbal
Flow of magnetorheological uids
Micromechanical modeling of a composite containing piezoelectric and shape
memory alloy inclusions
Adaptive imperfect column with piezoelectric actuators
Vibration suppression via smart structures across a temperature range
23
12(3) 2001
Mallavarapu K. Leo DJ.
Horner G. Taleghani B.
Lange U. Richter L. Zipser L.
Jiang B. Batra RC.
Alghamdi AAA.
Hegewald T. Inman DJ.
24
Journal of Intelligent Material Systems & Structures
207
209
215
223
229
235
247
259
265
271
277
283
289
295
The eleventh international conference on adaptive structures and technologies preface
Decentralized vibration control and coupled aeroservoelastic simulation of helicopter rotor blades with adaptive airfoils
Performance comparison between piezoelectric and elastomeric lag dampers on
ground resonance stability of helicopter
Miniature free-fall sensors
Material structure design of stress-dependent adaptive stiness
Use of piezoelectric shear response in adaptive sandwich shells of revolution - part
1: theoretical formulation
Use of piezoelectric shear response in adaptive sandwich shells of revolution - part
2: nite element implementation
Specic damping capacity of multiphase unidirectional hybrid ber composites
Improved surface treatment of sma foils and damage suppression of sma-foil embedded cfrp laminates
Mechanical property of metallic closed cellular materials containing organic material for passive damping and energy-absorbing systems
Simultaneous measurement of strain and temperature of structures using ber
optic sensor
Thermomechanical properties of polyurethane-shape memory polymer foam
Two-way shape memory behavior obtained by combined loading training
Analytical study on training eect of pseudoelastic transformation of shape memory alloys in cyclic loading
12(4) 2001
Matsuzaki Y.
Konstanzer P. Grohmann B. Kroplin B.
Kim SJ. Yun CY.
Hsu YH. Lee CK.
Tanaka M. Todoh M. Oki K. Naomi A.
Benjeddou A. Gorge V. Ohayon R.
Benjeddou A. Gorge V. Ohayon R.
Baburaj V. Matsuzaki Y. Nae FA. Ikeda T.
Ogisu T. Ando N. Takaki J. Okabe T. Takeda
N.
Kishimoto S. Shinya N.
Kang HK. Ryu CY. Hong CS. Kim CG.
Tobushi H. Okumura K. Endo M. Hayashi S.
Tokuda M. Sugino S. Inaba T.
Naito H. Sato J. Funami K. Matsuzaki Y.
Ikeda T.
Journal of Microelectromechanical Systems
2
12
20
27
36
45
54
61
68
78
85
91
An extraction-based verication methodology for mems
Measurements and modeling of two-phase ow in microchannels with nearly constant heat ux boundary conditions
Design considerations of rectangular electrostatic torsion actuators based on new
analytical pull-in expressions
The strain gradient eect in microelectromechanical systems (mems)
Electroosmotic ow control in complex microgeometries
Fabrication and characterization of hydrogel-based microvalves
Ink-jet printed nanoparticle microelectromechanical systems
A passive humidity monitoring system for in situ remote wireless testing of micropackages
Three-dimensional thin-lm shape memory alloy microactuator with two-way effect
A bidirectional magnetic microactuator using electroplated permanent magnet
arrays
Micromachining of glass inertial sensors
High-cycle fatigue of single-crystal silicon thin lms (vol 10, pg 593, 2001)
11(1) 2002
Baidya B. Gupta SK. Mukherjee T.
Zhang L. Koo JM. Jiang L. Asheghi M. Goodson KE. Santiago JG. Kenny TW.
Degani O. Nemirovsky Y.
Xue ZY. Saif MTA. Huang YG.
Dutta P. Beskok A. Warburton TC.
Liu RH. Yu Q. Beebe DJ.
Fuller SB. Wilhelm EJ. Jacobson JA.
Harpster TJ. Hauvespre S. Dokmeci MR. Naja K.
Gill JJ. Ho K. Carman GP.
Cho HJ. Ahn CH.
Belloy E. Sayah A. Gijs MAM.
Muhlstein CL. Brown SB. Ritchie RO.
Journal of Non-Newtonian Fluid Mechanics
1
45
65
A new nite element scheme using the lagrangian framework for simulation of
viscoelastic uid ows
A nite deformation formulation of the 3-parameter viscoelastic uid
Highly elastic solutions for oldroyd-b and phan-thien/tanner uids with a nite
volume/element method: planar contraction ows
103(1) 2002
Petera J.
Balan C. Tsakmakis C.
Aboubacar M. Matallah H. Webster MF.
Journal of Sound & Vibration
417
429
447
465
483
499
A method to predict acoustic radiation from an enclosed multicavity structure
Analysis of the response of a cracked jecott rotor to axial excitation
Vibration and stability of annular plates in non-linear creep conditions
Asymptotic approach for non-linear periodical vibrations of continuous structures
Dynamic response of two rotors connected by rigid mechanical coupling with
parallel misalignment
Analysis of the exural vibration of a thin-plate box using a combination of nite
element analysis and analytical impedances
249(3) 2002
Wu JH. Chen HL.
Darpe AK. Chawla A. Gupta K.
Gajewski A.
Andrianov IV. Danishevskyy VV.
Al-Hussain KM. Redmond I.
Grice RM. Pinnington RJ.
529
543
557
575
599
606
611
622
Chaotic dynamics of repeated impacts in vibratory bowl feeders
Stochastic dynamic sensitivity of uncertain structures subjected to random earthquake loading
On the origins and development of mobility and impedance methods in structural
dynamics [review]
Development and validation of reaction wheel disturbance models: empirical
model
On the behavior of dissipative time integration methods near the resonance condition
Dynamic analysis of an active exible suspension system
Robustness analysis of an environmental active noise control system
Preliminary computations for chatter control in end milling
Han I. Lee Y.
Bhattacharyya B. Chakraborty S.
Gardonio P. Brennan MJ.
Masterson RA. Miller DW. Grogan RL.
Cannillo V. Mancuso M.
Sun YG. Song KJ. Mao YH.
Yang J. Tan SE. Gan WS.
Semercigil SE. Chen LA.
Journal of Sound & Vibration
635
649
663
679
701
719
743
775
785
815
824
828
832
Alternative vibration protecting systems for men-operators of transport machines:
modern level and prospects
Experimental study on the vortex-induced vibration of towed pipes
Structural response of laminated composite shells subjected to blast loading: comparison of experimental and theoretical methods
Noise generated by a coanda wall jet circulation control device
Non-linear vibration absorber for a system under sinusoidal and random excitation: experiments
Merging sensor data from multiple measurement set-ups for non-stationary
subspace-based modal analysis
Non-linear modelling of rotor dynamic systems with squeeze lm dampers - an
eÆcient integrated approach
A synthetic analysis on design of optimum control for an optimized intelligent
structure
A comparison of three techniques using steady state data to identify non-linear
modal behavior of an externally excited cantilever beam
Eect of non-ideal boundary conditions on the vibrations of continuous systems
On the propagation of plane sound waves in ducts carrying an incompressible
axial mean ow having an arbitrary velocity prole
Road traÆc noise annoyance and window orientation in dwellings
Comments on "stochastic model on a rattling system"
249(4) 2002
Lee CM. Goverdovskiy VN.
Hong S. Choi YR. Park JB. Park YK. Kim
YH.
Turkmen HS.
Howe MS.
Cuvalci O. Ertas A. Ekwaro-Osire S. Cicek I.
Mevel L. Basseville M. Benveniste A. Goursat
M.
Bonello P. Brennan MJ. Holmes R.
Yan YJ. Yam LH.
Doughty TA. Davies P. Bajaj AK.
Pakdemirli M. Boyaci H.
Dokumaci E.
Rylander R. Bjorkman M.
Dai DC.
Journal of Sound & Vibration
835
849
867
885
899
909
921
939
955
971
995
999
1011
Adaptive-passive absorbers using shape-memory alloys
Physical interpretation of the proper orthogonal modes using the singular value
decomposition
Selection of training samples for model updating using neural networks
Acoustic power suppression of a panel structure using h-innity output feedback
control
Oscillation-sliding in a modied van der pol-duÆng electronic oscillator
Normal mode localization for a two degrees-of-freedom system with quadratic and
cubic non-linearities
Dynamic traction vector eld estimation in a structure using hybrid strain analysis
Wavenumber prediction of waves in buried pipes for water leak detection
Extraction of structural system matrices from an identied state-space system
using the combined measurements of dva
A new galerkin-based approach for accurate non-linear normal modes through
invariant manifolds
Period preservation and period adjustment in the numerical integration of the
linear and non-linear equations of motion
Vibration parameters for damage detection in structures
Comments on "vibration analysis of thin cylindrical shells using the wave propagation approach"
25
249(5) 2002
Williams K. Chiu G. Bernhard R.
Kerschen G. Golinval JC.
Chang CC. Chang TYP. Xu YG. To WM.
Sivrioglu S. Tanaka N. Yuksek I.
Algaba A. Fernandez-Sanchez F. Freire E.
Gamero E. Rodriguez-Luis AJ.
Bhattacharyya R. Jain P. Nair A.
Sehlstedt N.
Muggleton JM. Brennan MJ. Pinnington RJ.
Ko WJ. Hung CF.
Pesheck E. Pierre C. Shaw SW.
Fried I.
Palacz M. Krawczuk M.
Wang C. Lai JCS.
26
Journal of Sound & Vibration
1
5
9
23
31
41
47
53
65
75
83
91
101
107
115
119
129
139
145
151
157
161
169
175
Fourth japanese-swedish noise symposium on medical eects, rosenon, stockholm,
sweden, 16-19 august 2000
Current research topics and problems: the role of icben
Diagnostic system based on the human auditory-brain model for measuring environmental noise - an application to railway noise
Psycho-circulatory responses caused by listening to music, and exposure to uctuating noise or steady noise
Duration sensation when listening to bandpass noises
Relation between the overall impression of the sound environment and types and
loudness of environmental sounds
Loudness of sharply (2068 db/octave) ltered noises in relation to the factors
extracted from the autocorrelation function
Annoyance and spectral contrast are cues for similarity and preference of sounds
Psycho-acoustic characters of relevance for annoyance of wind turbine noise
Sleep time monitoring by accelerometer in two subjects for 1 year
The eect of dierent kinds of noise on the quality of sleep under the controlled
conditions
Dierent eects of road traÆc noise and frogs' croaking on night sleep
Habituation of sleep to road traÆc noise observed not by polygraphy but by
perception
Habituation of sleep to a ship's noise as determined by actigraphy and a sleep
questionnaire
Protecting against noise trauma by sound conditioning
Self-evaluation scores of hearing diÆculties and quality of life components among
retired workers with noise-related hearing loss
Population-based questionnaire survey on health eects of aircraft noise on residents living around us airelds in the ryukyus - part 1: an analysis of 12 scale
scores
Population-based questionnaire survey on health eects of aircraft noise on residents living around us airelds in the ryukyus - part ii: an analysis of the discriminant score and the factor score
Distribution of blood pressure data from people living near an airport
Adverse health eects in relation to urban residential soundscapes
Road traÆc noise inuenced by road bumps
Comparison of community response to road traÆc noise in japan and sweden part i: outline of surveys and dose-response relationships
Comparison of community response to road traÆc noise in japan and sweden part ii: path analysis
Planning consequences of the maximum db(a) concept - a perspective
250(1) 2002
Rylander R. Ando Y.
Gjestland T.
Sakai H. Hotehama T. Ando Y. Prodi N. Pompoli R.
Sakamoto H. Hayashi F. Sugiura S. Tsujikawa
M.
Ando Y. Saifuddin K. Sato S.
Kawai K. Yano T.
Sato S. Kitamura T. Ando Y.
Berglund B. Hassmen P. Preis A.
Waye KP. Ohrstrom E.
Kawada T. Kuroiwa M. Sasazawa Y. Suzuki S.
Tamura Y.
Kuwano S. Mizunami T. Namba S. Morinaga
M.
Sasazawa Y. Xin P. Suzuki S. Kawada T.
Kuroiwa M. Tamura Y.
Kuroiwa M. Xin P. Suzuki S. Sasazawa Y.
Kawada T. Tamura Y.
Tamura Y. Horiyasu T. Sano Y. Chonan K.
Kawada T. Sasazawa Y. Kuroiwa M. Suzuki
S.
Niu X. Canlon B.
Miyakita T. Ueda A. Zusho H. Kudoh Y.
Miyakita T. Matsui T. Ito A. Tokuyama T.
Hiramatsu K. Osada Y. Yamamoto T.
Hiramatsu K. Matsui T. Miyakita T. Ito A.
Tokuyama T. Osada Y. Yamamoto T.
Goto K. Kaneko T.
Skanberg A. Ohrstrom E.
Rylander R. Bjorkman M.
Sato T. Yano T. Bjorkman M. Rylander R.
Yano T. Sato T. Bjorkman M. Rylander R.
Rylander R. Bjorkman M.
Journal of Sound & Vibration
181
197
215
229
247
277
299
323
339
351
356
368
Measurement of the viscoelastic properties of damping materials: adaptation of
the wave propagation method to test samples of short length
Reducing operator-induced machine vibration using a complex pole/zero prelter
Dispersion of waves in immersed laminated composite hollow cylinders
Chaos and multiple periods in an unsymmetrical spring and damping system with
clearance
Energy transfer for high frequencies in built-up structures
Whistles with a generic sidebranch: production and suppression
Eects of end cap and aspect ratio on transmission of sound across a truss-like
periodic double panel
Combination of nite and boundary element methods in investigation and prediction of load-controlled noise of power transformers
Normal modes of a non-linear clamped-clamped beam
Coupling loss factors for coupled anisotropic plates
Stability analysis of spinning stepped-shaft workpieces in a turning process
Natural frequencies of tensioned pipes conveying uid and carrying a concentrated
mass
250(2) 2002
Lemerle P.
Ingram GA. Franchek MA. Chiu GTC.
Xi ZC. Liu GR. Lam KY. Shang HM.
Hossain MZ. Mizutani K. Sawai H.
Le Bot A.
Selamet A. Kurniawan D. Knotts BD. Novak
JM.
El-Raheb M. Wagner P.
Rausch M. Kaltenbacher M. Landes H. Lerch
R. Anger J. Gerth J. Boss P.
Xie WC. Lee HP. Lim SP.
Bosmans I. Vermeir G. Mees P.
Wang ZC. Cleghorn WL.
Oz HR. Evrensel CA.
27
Journal of Sound & Vibration
379
401
415
431
445
465
485
503
519
541
567
569
575
Measurement and analysis of modulated doublet mode response in mock bladed
disks
Dynamic stability of skew plates subjected to aerodynamic and random in-plane
forces
The application of ball-type balancers for radial vibration reduction of high-speed
optic disk drives
High-frequency radiation of l-shaped plates by a local energy ow approach
Dynamic stability problem of a non-prismatic rod
An approach to parameter identication for a single-degree-of-freedom dynamical
system based on short free acceleration response
Active impact control system design with a hydraulic damper
Exact buckling and vibration solutions for stepped rectangular plates
Passive damping augmentation of a vibrating beam using pseudoelastic shape
memory alloy wires
Coincidence of thermoelastic and thermoviscous acoustic waves in uid-lled elastic tubes
More on generalized harmonic oscillators
Transverse vibrations of rectangular plates of generalized anisotropy and discontinuously varying thickness
Transverse vibrations of clamped and simply supported circular plates of deformed boundaries
250(3) 2002
Chang JY. Wickert JA.
Young TH. Lee CW. Chen FY.
Huang WY. Chao CP. Kang JR. Sung CK.
Cotoni V. Le Bot A. Jezequel L.
Ruta P.
Jaksic N. Boltezar M.
Kim DH. Park JW. Lee GS. Lee KI.
Xiang Y. Wang CM.
Gandhi F. Chapuis G.
Liang PN. Scarton HA.
Hu H.
Laura PAA. Gutierrez RH.
Gutierrez RH. Laura PAA. Rossi RE.
Journal of Sound & Vibration
579
591
609
617
627
649
675
711
723
745
762
Experimental active control of automotive disc brake rotor squeal using dither
Control of multi-span beam vibration by a random wave reector
Dynamic analysis of delayed damper system in engineering structures
Modelling and control with piezoactuators for a simply supported beam under a
moving mass
An investigation of power ow characteristics of l-shaped plates adopting a substructure approach
Forced vibrations of triply coupled, periodically and elastically supported, nite,
open-section channels
Vibration of a compliant tower in three-dimensions
Wave propagation through a cylindrical bore contained in a microstretch elastic
medium
Model comparison for acoustic scattering by a spherical air bubble in water
Loss factors of composite honeycomb sandwich panels
Design of a novel cryptosystem based on chaotic oscillators and feedback inversion
250(4) 2002
Cunefare KA. Graf AJ.
Xu MB. Huang L.
Chen D. Xu H.
Sung YG.
Wang ZH. Xing JT. Price WG.
Yaman Y. Ozdemir O.
Han SM. Benaroya H.
Kumar R. Deswal S.
Wang CC. Ye Z.
Renji K. Narayan SS.
Shahruz SM. Pradeep AK. Gurumoorthy R.
Journal of Strain Analysis for Engineering Design
1
13
21
33
47
59
73
87
Prediction of fold eccentricity in the axial axisymmetric plastic progressive collapse of circular tubes
Determination of residual stress using critically refracted longitudinal waves and
immersion mode
Development of the alternating current stress measurement model for magnetostriction behaviour of mild steel under orthogonal magnetic elds for stress
measurement
Elastic-plastic analyses for surface cracked plates under combined bending and
tension
A parametric study of inclusion interaction in particulate- and bre-reinforced
materials using the boundary element technique
Identication of the sources of non-adiabatic behaviour for practical thermoelastic
stress analysis
Analysis of neutron diraction strain measurement data from a round robin sample
Small sample theory for reliability design
37(1) 2002
Avalle M. Belingardi G.
Belahcene F. Lu J.
Han S. Brennan FP. Dover WD.
Kim YJ. Shim DJ. Choi JB.
Knight MG. de Lacerda LA. Henshall JL. Wrobel LC.
Quinn S. Dulieu-Barton JM.
Daymond MR. Johnson MW. Sivia DS.
Xiong J. Shenoi RA. Gao Z.
28
Journal of Thermal Stresses
215
245
265
283
295
Transient thermoelastic analysis of disk brake using the fast fourier transform
and nite element method
Stabilized ux-based ow/thermal nite element representations with applications to convectively cooled structures
An inverse problem of coupled thermoelasticity in predicting heat ux and thermal stresses by strain measurement
A macroscopic model for the heat propagation in the microperiodic composite
solids
State space approach to two-dimensional generalized thermoviscoelasticity with
one relaxation time
25(3) 2002
Cho CD. Ahn S.
Poon WS. Tamma KK.
Yang YC. Chen UC. Chang WJ.
Wozniak C. Wierzbicki E. Wozniak M.
Ezzat MA. Othman MI. El-Karamany AS.
Journal of Thermal Stresses
319
341
363
373
389
Multidisciplinary ow/thermal and induced stresses in convectively cooled structures
Thermoelastic interactions in a transversely isotropic elastic medium with a cylindrical hole subjected to ramp-type increase in boundary temperature or load
Thermal elastic-plastic stress analysis of symmetric aluminum metal-matrix composite laminated plates under uniformly distributed temperature
The inuence of crack-face uid pressure on the fatigue crack propagation due to
rolling contact with frictional heat
Thermal stress analysis in thermopiezoelastic strip with an edge crack
25(4) 2002
Poon WS. Kanapady R. Mohan RV. Tamma
KK.
Mukhopadhyay S.
Sayman O. Sayman S.
Goshima T. Ishihara S. Shimizu M.
Niraula OP. Noda N.
Journal of Vibration & Control
3
13
19
41
51
69
87
Prediction of structure-borne sound in orthotropic plates for far-eld conditions
Stability for hopeld neural networks with time delay
Enhanced proper orthogonal decomposition for the modal analysis of homogeneous structures
A mathematical model for pseudoelasticity of shape memory alloy and its application in passive control
Vibration analysis of rotor for crack identication
Vibration control of unknown exible beam structures
Nonlinear modeling, experimental verication, and theoretical analysis of a hydraulic engine mount
8(1) 2002
Mandal NK. Leong MS. Abd Rahman R.
Wang LS. Xu DY.
Han S. Feeny BF.
Wei Z. Ma HY. Sun DC.
Saavedra PN. Cuitino LA.
Mohammad KS. Al-Dmour AS.
Jazar GN. Golnaraghi MF.
JSME International Journal Series A
-Solid Mechanics & Material Engineering
1
2
8
Special issue on creep and fatigue at elevated temperatures
Creep behavior of ir-nb and ir-zr refractory superalloys
Creep behavior of ir-nb-ni two-phase refractory superalloy
14
Creep behavior of 8cr2wvta martensitic steel designed for fusion demo reactor*
(an assessment on helium embrittlement resistance)
Creep behavior of orthorhombic ti(2)ainb based intermetallic alloys
Eects of w and co on the microstructure and creep strength of the precipitation
strengthened 15cr ferritic steels
Inuence of pre-aging on creep rupture strength of tungsten alloyed 9cr ferritic
steel and creep damage evaluation by electrochemical method
Nondestructive evaluation of creep damage using leaky surface acoustic wave
technique
High temperature low cycle fatigue of 2 1/4 cr1mo steels: role of microstructure
and eect of environment
Study on creep-fatigue life of irradiated austenitic stainless steel
20
25
30
39
46
51
57
65
72
77
Thermal fatigue in thermal barrier coating
On time-dependent crack growth parameters in plasticity and creep elds
Evaluation of creep damage due to void growth under triaxial stress states in the
design of steam turbine components
Shear correction factors in creep-damage analysis of beams, plates and shells
45(1) 2002
Nitta A.
Yamabe-Mitarai Y. Nakazawa S. Harada H.
Gu YF. Yamabe-Mitarai Y. Nakazawa S.
Harada H.
Yamamoto N. Murase Y. Nagakawa J. Shiba
K.
Tang F. Nakazawa S. Hagiwara M.
Toda Y. Seki K. Kimura K. Abe F.
Komazaki S. Kishi S. Shoji T. Kumazawa T.
Higuchi K. Suzuki K.
Yokono Y. Nagano Y. Mukai K. Imanaka T.
Vogt JB. Sosa JL. Argillier S.
Ioka I. Miwa Y. Tsuji H. Yonekawa M. Takada
F. Hoshiya T.
Zhou YC. Hashida T.
Kim KS. Han C.
Wichtmann A.
Altenbach H. Naumenko K.
84
90
98
104
110
Finite element creep continuum damage mechanics analysis of pressurised pipe
bends with ovality
The use of cdm analysis techniques in high temperature creep failure of welded
structures
Advances in the use of stress relaxation data for design and life assessment in
combustion turbines
Development of a ller metal for weldments of a ni-cr-w superalloy with high
creep strength
Development of 18cr-9ni-w-nb-v-n austenitic stainless steel tube for thermal
power boilers
Hyde TH. Yaghi A. Becker AA. Earl PG.
Hayhurst DR. Wong MT. Vakili-Tahami F.
Woodford DA.
Kurata Y. Saito T. Tsuji H. Takatsu T. Shindo
M. Nakajima H.
Ishitsuka T. Mimura H.
JSME International Journal Series C
-Mechanical Systems Machine Elements & Manufacturing
914
920
928
937
946
952
958
964
972
982
990
996
1005
1013
1021
1031
1041
1051
1059
1065
1072
1082
1089
1097
1103
1111
1117
1125
1133
Eect of actin lament on deformation-induced ca2+ response in osteoblast-like
cells
Dynamic response to mechanical stimulation in myoblasts
Large deformation mechanics of plasma membrane chained vesicles in cells
Improvement in the viability of cryopreserved cells by microencapsulation
Thrust force characteristics of propulsion mechanism modeled on bending mechanism of eukaryotic agella in water
Optimum shape of a agellated microorganism
Comparison between observation and boundary element analysis of bacterium
swimming motion
Proposal of a deformable erythrocyte model and numerical analysis of shear ow
of blood
Measurement of surface topography of endothelial cell and wall shear stress distribution on the cell
Numerical simulation system for blood ow in the cerebral artery using ct imaging
data
Flow around cells adhered to a microvessel wall. iii. eects of neighboring cells
in channel ow
Changes in water ltration velocity and wall structure of the rabbit common
carotid artery after removal of the adventitia
Mass transport in pulsatile ow through asymmetric stenosis
Relationship between intraventricular ow patterns and the shapes of the aliasing
area in color m-mode doppler echocardiograms - a cfd study with an axisymmetric, model of the lv
The eect of creating a moderate stenosis on the localization of intimal thickening
in the common carotid artery of the rabbit fed on a cholesterol-rich diet
Fundamental investigation for developing drug delivery systems and bioprocess
with shock waves and bubbles - (numerical analysis of deformation of cell model
and observation of bubble behaviour near the cell-membrane model)
Secondary, ow augmentation during intermittent oscillatory ow in model human central airways
Mechanical evaluation of reconstructed structures after total sacrectomy and their
improvement
Study on treatment with respect to idiopathic scoliosis - (sensitivity analysis
based on buckling theory)
Thermoelastic femoral stress imaging for experimental evaluation of hip prosthesis
design
Development of a nite element model of the human shoulder to investigate the
mechanical responses and injuries in side impact
Dynamic evaluation of the contact characteristics and three-dimensional motion
for the ankle joint with lateral ligament injuries
Eects of knee and ankle movements on foot impact forces in human walking
Eect of depth of conical-shaped tympanic membrane on middle-ear sound transmission
The wing apparatus and apping behavior of hymenoptera
Interlaminar reinforcement mechanism in a beetle fore-wing
Experimental study on oscillating wing for propulsor with bending mechanism
modeled on caudal muscle-skeletal structure of tuna
A method for gait analysis in a daily living environment by body-mounted instruments
A study of an emg-based exoskeletal robot for human shoulder motion support
29
44(4) 2001
Adachi T. Murai T. Hoshiai S. Tomita Y.
Murakami S. Homma K. Atomi Y.
Kosawada T. Sanada K. Takano T.
Matsumoto Y. Morinaga Y. Ujihira M. Oka K.
Tanishita K.
Kobayashi S. Nakasone M. Furihata K.
Morikawa H.
Fujita T. Kawai T.
Goto T. Masuda S. Terada K. Takano Y.
Ishikawa T. Kawabata N. Tachibana M.
Fukushima S. Nagatsu A. Kaibara M. Oka K.
Tanishita K.
Torii R. Oshima M. Kobayashi T. Takagi K.
Sugihara-Seki M.
Wada S. Kaichi M. Karino T.
Ishikawa T. Oshima S. Yamane R.
Nakamura M. Wada S. Mikami T. Kitabatake
A. Karino T.
Wada S. Koujiya M. Karino AT.
Tamagawa M. Yamanoi I. Matsumoto A.
Tanaka G. Kotaro OKA. Tanishita K.
Sakamoto J. Oda J. Nagashima Y. Yoshida A.
Murakami H. Kawahara N. Tomita K.
Takeuchi K. Azegami H. Murachi S. Kitoh J.
Ishida Y. Kawakami N. Makino M.
Hyodo K. Inomoto M. Ma W. Miyakawa S.
Tateishi T.
Iwamoto M. Miki K. Yang KH.
Kawakami K. Omori G. Terashima S.
Sakamoto M. Hara T.
Tagawa Y. Shiba N. Miyazaki K. Matsuo S.
Inoue A. Yamashita T.
Koike T. Wada H. Kobayashi T.
Sudo S. Tsuyuki K. Ito Y. Tani J.
Ni QQ. Chen JX. Iwamoto M. Kurashiki K.
Saito K.
Morikawa H. Nakao S. Kobayashi SI.
Ohtaki Y. Sagawa K. Inooka H.
Kiguchi K. Iwami K. Watanabe K. Fukuda T.
30
1142
1152
Identication of control parameters for brass player's embouchure by measuring
contact pressure on the teeth buccal surface
Investigation on a temperature control system modeled after the function of the
skin - (on the temperature control system by the operation of ow rate allotment)
Kourakata I. Moriyama K. Hara T.
Nakamura M. Shoji S. Suzuki R. Yamada E.
Meccanica
243
251
265
273
291
297
Wear of an elastic block
Similarity solutions for thawing processes with a heat ux condition at the xed
boundary
Euler's problem revisited: 222 years later
On generalised and implicit normality hypotheses
Stochastic sensitivity analysis of structures using rst-order perturbation
Nonlinearity in uid resonances [review]
36(3) 2001
Villaggio P.
Lombardi AL. Tarzia DA.
Elishako I.
Bodoville G.
Ghosh R. Chakraborty S. Bhattacharyya B.
Ockendon H. Ockendon JR.
Mechanics of Materials
75
97
117
127
An improved hyperelasticity relation in modeling viscoelasticity response of natural and high damping rubbers in compression: experiments, parameter identication and numerical verication
An eective stress elastic-plastic model for unsaturated porous media
Two-dimensional analysis on elastic strain energy due to a uniformly eigenstrained
supercircular inclusion in an elastically anisotropic material
Eect of plastic prestrain on high cycle fatigue of ti-6al-4v
34(2) 2002
Amin AFMS. Alam MS. Okui Y.
Loret B. Khalili N.
Onaka S. Kobayashi N. Kato M.
Lanning DB. Nicholas T. Haritos GK.
Mechanics of Structures & Machines
0
1
31
83
103
123
Special issue on symbolic computing in multibody dynamics - preface
Symbolic-numeric analysis of exible multibody systems
Fully symbolic generation of complex multibody models
On the foreshortening eects of a rotating exible beam using dierent modeling
methods
Symbolic methods for systems of implicit ordinary dierential equations
Symbolic programming of a graph-theoretic approach to exible multibody dynamics
30(1) 2002
McPhee J.
Claus H. Schiehlen W.
Fisette P. Postiau T. Sass L. Samin JC.
Piedboeuf JC. Moore B.
Schlacher K. Kugi A.
Shi PF. McPhee J.
Mechanics Research Communications
601
611
617
623
629
637
653
671
679
685
693
703
Attitude drift toward collinearity of a wayward planet
Age eect investigation on postural dynamic responses of human body
A general solution procedure for coupled systems with arbitrary internal resonances
Investigation of laminar ow through solution of inverse problem for heat conduction equation
Finite element formulation of 3-d heat transfer problem for orthotropic materials
Coupled thermomechanical dynamics of phase transitions in shape memory alloys
and related hysteresis phenomena
A new approach for the slope stability analysis
The state vector solution of axisymmetric biot's consolidation problems for multilayered poroelastic media
Bleustein-gulyaev waves in strained piezoelectric ceramics
The electrostrictive eect on wave propagation in isotropic solids subjected to
initial elds
Finite viscoelasticity, plasticity and damage of a class of lled elastomers: constitutive model
Closed-form solution for a mode-iii crack at the mid-plane of a piezoelectric layer
28(6) 2001
Rimrott FPJ. Salustri FA.
Hoviattalab M.
Pakdemirli M.
Cialkowski M. Frackowiak A. Kolodziej JA.
Yan XQ. Yu ZX.
Melnik RVN. Roberts AJ. Thomas KA.
Yang HJ. Wang JH. Liu YQ.
Wang JG. Fang SS.
Yang JS.
Simionescu-Panait O.
Bikard J. Desoyer T.
Li XF. Duan XY.
Nonlinear Dynamics
1
3
Untitled - preface
Invariant manifolds, nonclassical normal modes, and proper orthogonal modes in
the dynamics of the exible spherical pendulum
25(1-3) 2001
Vakakis AF.
Georgiou IT. Schwartz IB.
33
49
65
79
95
111
133
157
183
207
221
237
255
275
Normal vibrations in near-conservative self-excited and viscoelastic nonlinear systems
Nonlinear normal modes in a system with nonholonomic constraints
Nonlinear normal modes of a parametrically excited cantilever beam
Normal modes and boundary layers for a slender tensioned beam on a nonlinear
foundation
The description of localized normal modes in a chain of nonlinear coupled oscillators using complex variables
Spatially localized models of extended systems
Mode localization in dynamics and buckling of linear imperfect continuous structures
Dynamics of relative phases: generalised multibreathers
Nonlinear modal analysis of structural systems using multi-mode invariant manifolds
Localization in nonlinear mistuned systems with cyclic symmetry
Mode localization induced by a nonlinear control loop
Transition of energy to a nonlinear localized mode in a highly asymmetric system
of two oscillators
Application of nonlinear normal mode analysis to the nonlinear and coupled dynamics of a oating oshore platform with damping
Performance of nonlinear vibration absorbers for multi-degrees-of-freedom systems using nonlinear normal modes
Rand RH. Ramani DV.
Yabuno H. Nayfeh AH.
Pellicano F. Vakakis AF.
Manevitch LI.
Wittenberg RW. Holmes P.
Luongo A.
Ahn T. MacKay RS. Sepulchre JA.
Pesheck E. Boivin N. Pierre C. Shaw SW.
Sextro W. Popp K. Krzyzynski T.
M'Closkey RT. Vakakis A. Gutierrez R.
Gendelman OV.
Falzarano JM. Clague RE. Kota RS.
Agnes GS. Inman DJ.
Nonlinear Dynamics
293
317
333
355
369
383
Bifurcation analysis of parametrically excited rayleigh-lienard oscillators
Dimensional reduction for nonlinear time-delayed systems composed of sti and
soft substructures
Passive transient wave connement due to nonlinear joints in coupled exible
systems
Resonance and stochastic layer in a parametrically excited pendulum
Local bifurcation control of a forced single-degree-of-freedom nonlinear system:
saddle-node bifurcation
Fault identication in rotating machinery using the correlation dimension and
bispectra
25(4) 2001
Maccari A.
Wang ZH. Hu HY.
Nayfeh TA. Vakakis AF.
Luo ACJ.
Ji JC.
Wang WJ. Wu ZT. Chen J.
Nonlinear Dynamics
1
3
23
45
67
87
In memory of ross m. evan-iwanowski - october 2, 1914-march 18, 2001
An eigenvalue method for calculation of stability and limit cycles in nonlinear
systems
Hopf bifurcation and stability of periodic solutions for van der pol equation with
distributed delay
A second-order approximation of multi-modal interactions in externally excited
circular cylindrical shells
Practical evaluation of invariant measures for the chaotic response of a twofrequency excited mechanical oscillator
Nonlinear vibration of plane structures by nite element and incremental harmonic balance method
26(1) 2001
Sinha SC.
Somieski G.
Liao XF. Wong KW. Wu ZF.
Chin CM. Nayfeh AH.
Nichols JM. Virgin LN.
Chen SH. Cheung YK. Xing HX.
Nonlinear Dynamics
105
121
143
163
179
The response of a parametrically excited van der pol oscillator to a time delay
state feedback
Subcritical hopf bifurcation in the delay equation model for machine tool vibrations
Stabilization of the parametric resonance of a cantilever beam by bifurcation
control with a piezoelectric actuator
Transverse vibrations of a centrally clamped rotating circular disk
A survey of rail vehicle track simulations and exible multibody dynamics [review]
31
Mikhlin YV. Morgunov BI.
26(2) 2001
Maccari A.
Kalmar-Nagy T. Stepan G. Moon FC.
Yabuno H. Saigusa S. Aoshima N.
Nayfeh AH. Jilani A. Manzione P.
Shabana AA. Sany JR.
32
Nonlinear Dynamics
211
231
253
273
297
The response of a rayleigh-lienard oscillator to a fundamental resonance
Eect of unsteady wind ow on galloping of tall prismatic structures
Distinguishing periodic and chaotic time series obtained from an experimental
nonlinear pendulum
Nonlinear dynamics of two-degrees-of-freedom uid conveying elasto-visco-plastic
model system
Non-local periodic motions of a thin cantilevered rod
26(3) 2001
Maccari A.
Abdel-Rohman M.
Franca LFP. Savi MA.
Terentiev AV.
MacEwen KW.
Nonlinear Dynamics
309
331
351
371
393
Approximate rst integrals of weakly nonlinear, damped-driven oscillators with
one degree of freedom
Uniform convergence series to solve nonlinear partial dierential equations: application to beam dynamics
Nonlinear frequency response of nonisothermal adsorption systems
3d dynamic modelling of spatial geared systems
Thermally induced, nonlinear vibrations of rotating disks
26(4) 2001
Unal G.
Filipich CP. Rosales MB.
Petkovska M.
Wang Y. Cheung HME. Zhang WJ.
Saniei N. Luo ACJ.
Nonlinear Dynamics
1
19
55
69
87
Eect of nonlinear stiness on the motion of a exible pendulum
Analysis on double hopf bifurcation using computer algebra with the aid of multiple scales
Multiple equilibria and their eects on impact damage in an air-handling assembly
Formulation of a hysteretic restoring force model. application to vibration isolation
Global behavior of a nonlinear quasiperiodic mathieu equation
27(1) 2002
Zaki K. Noah S. Rajagopal KR. Srinivasa AR.
Yu P.
McGee CG. Adams DE.
Al Majid A. Dufour R.
Zounes RS. Rand RH.
Nonlinear Dynamics
107
185
197
Nonlinear dynamics of oating cranes
Type-i intermittency and crisis-induced intermittency in a semiconductor laser
under injection current modulation
Optimal control of populations of competing species
27(2) 2002
Ellermann K. Kreuzer E. Markiewicz M.
Manra EF. Caldas IL. Viana RL. Kalinowski
HJ.
Crespo LG. Sun JQ.
Nonlinear Dynamics
211
237
255
271
295
Quasi-periodic solutions and stability for a weakly damped nonlinear quasiperiodic mathieu equation
On the proper form of the amplitude modulation equations for resonant systems
Pendulation reduction in boom cranes using cable length manipulation
Common features of the onset of the persistent chaos in nonlinear oscillators: a
phenomenological approach
Robust feedback stabilization of limit cycles in pwm dc-dc converters
Proceedings of the Royal Society of London Series AMathematical, Physical and Engineering Sciences
255
271
283
299
319
339
359
381
On the stability of the upside-down pendulum with damping
Solution of the generalized riemann problem for advection-reaction equations
Secondary boundary layer and wall shear for fully developed ow in curved pipes
Non-convex potentials and microstructures in nite-strain plasticity
Conserved currents, superpotentials and cosmological perturbations
Vibrations of a shallow cable with a viscous damper
A framework for perturbations and stability of dierentially rotating stars
Yoe-type moving crack in a functionally graded piezoelectric material
27(3) 2002
Guennoun K. Houssni M. Belhaq M.
Luongo A. Di Egidio A. Paolone A.
Abdel-Rahman EM. Nayfeh AH.
Szemplinska-Stupnicka W. Tyrkiel E.
Fang CC. Abed EH.
458(2018) 2002
Bartuccelli MV. Gentile G. Georgiou KV.
Toro EF. Titarev VA.
Dey S.
Carstensen C. Hackl K. Mielke A.
Petrov AN. Katz J.
Krenk S. Nielsen SRK.
Beyer HR.
Li CY. Weng GJ.
401
429
451
473
489
Numerical solution for diraction of an electromagnetic wave by slits in a perfectly
conducting screen
Multi-dimensional solutions of space-time-fractional diusion equations
Pauli's theorem and quantum canonical pairs: the consistency of a bounded, selfadjoint time operator canonically conjugate to a hamiltonian with non-empty
point spectrum
Unsteady pressure elds which precede the launch of free-surface liquid jets
A vector potential and exact ux through surfaces using lagrange and stokes
stream functions
Hanyga A.
Galapon EA.
Cooker MJ.
Steward DR.
Quarterly Journal of Mechanics & Applied Mathematics
1
17
29
49
69
93
109
127
141
Courant's nodal line theorem and its discrete counterparts
Some aspects of nite amplitude transverse waves in a compressible hyperelastic
solid
The cantilever strip plate of varying thickness and the centre of shear
Interference and turning of in-parallel wakes
Hysteresis in the stress-cycling of bars undergoing solid-solid phase transitions
Wave reection and transmission from anisotropic layers through riccati equations
Small-amplitude inhomogeneous plane waves in a deformed mooney-rivlin material
On the non-existence of surface waves trapped by submerged obstructions having
exterior cusp points
Two asymptotic forms of the rotational solution for wave propagation inside viscous channels with transpiring walls
33
Nye JF.
55(Part 1) 2002
Gladwell GML.
Haddow JB. Erbay HA.
Gregory RD. Gu CC. Wan FYM.
Smith FT.
Knowles JK.
Caviglia G. Morro A.
Destrade M.
Motygin V.
Majdalani J. Rienstra SW.
Quarterly of Applied Mathematics
1
11
37
75
87
99
111
131
153
183
195
A note on the persistence of leading n-waves of tsunami
Theory of exact solutions for the evolution of a uid annulus in a rotating heleshaw cell
A geometric evolution problem
Convex polyhedra quantum billiards in r-n
"forbidden" planes for rayleigh waves
On derivative of energy functional for elastic bodies with cracks and unilateral
conditions
Stabilization of the korteweg-de vries equation with localized damping
A mathematical analysis of electrical discharges
Maximum recoverable work, minimum free energy and state space in linear viscoelasticity
Existence and uniqueness of solutions of smoluchowski's coagulation equation
with source terms
Uniqueness and construction of solution for the nonlinear elastodiusion problem
60(1) 2002
Kovalyov M.
Crowdy D.
Bergwall A.
Libo RL.
Kuznetsov SV.
Khludnev AM. Ohtsuka K. Sokolowski J.
Menzala GP. Vasconcellos CF. Zuazua E.
Severin F. Nouri A.
Gentili G.
Shirvani M. Van Roessel HJ.
Markensco X.
Rheologica Acta
1
10
25
35
45
55
61
77
87
93
Gelation study of high processability and high reliability ternary systems based on
benzoxazine, epoxy, and phenolic resins for an application as electronic packaging
materials
Eect of maleic anhydride content on the rheology and phase behavior of
poly(styrene-co-maleic anhydride)/poly(methyl methacrylate) blends
Surfactant-induced eects on turbulent swirling ows
Shear-banding structure orientated in the vorticity direction observed for equimolar micellar solution
Rheology and ow-birefringence from viscoelastic polymer-clay solutions
The eect of mixing particles of dierent size on the electrorheological response
under steady shear ow
The normal stress behaviour of suspensions with viscoelastic matrix uids
Quantitative rheological evaluation of phase inversion in two-phase polymer
blends with cocontinuous morphology
Coupling between ow and diusion at polymer/polymer interfaces: large amplitude oscillatory shear experiments
A network model with free-strand dynamics for polymer melts
41(1-2) 2002
Rimdusit S. Ishida H.
Chopra D. Kontopoulou M. Vlassopoulos D.
Hatzikiriakos SG.
Arora K. Sureshkumar R. Scheiner MP. Piper
JL.
Fischer P. Wheeler EK. Fuller GG.
Schmidt G. Nakatani AI. Han CC.
See H. Kawai A. Ikazaki F.
Mall-Gleissle SE. Gleissle W. McKinley GH.
Buggisch H.
Steinmann S. Gronski W. Friedrich C.
Qiu H. Bousmina M. Dealy JM.
Seimenis M. Wedgewood LE.
34
103
114
134
Van gurp-palmen plot ii - classication of long chain branched polymers by their
topology
Birefringence measurements on polymer melts in an axisymmetric ow cell
162
Extrusion of pastes with a piston extruder for the determination of the local
solid and uid concentration, the local porosity and saturation and displacement
proles by means of nmr imaging
Three-dimensional viscoelastic simulation of coextrusion process: comparison
with experimental data
Small and large strain rheology of wheat gluten
173
The rheology of bread dough made from four commercial ours
180
Viscoelastic properties of pig kidney in shear, experimental results and modelling
144
Trinkle S. Walter P. Friedrich C.
Harrison P. Janssen LJP. Navez VP. Peters
GWM. Baaijens FPT.
Gotz J. Kreibich W. Peciar M.
Sunwoo KB. Park SJ. Lee SJ. Ahn KH.
Uthayakumaran S. Newberry M. Phan-Thien
N. Tanner R.
Keentok M. Newberry MP. Gras P. Bekes F.
Tanner RI.
Nasseri S. Bilston LE. Phan-Thien N.
Studies in Applied Mathematics
1
7
29
39
65
77
89
105
123
145
Research contributions of david j. benney
On transition to turbulence and synthesis of alternative approaches
From disorder to order - august 2000
Wave turbulence is almost always intermittent at either small or large scales
Slow passage through the nonhyperbolic homoclinic orbit of the saddle-center
hamiltonian bifurcation
Long-wave instability in a three-layer stratied shear ow
Subcritical rossby waves in zonal shear ows with nonlinear critical layers
Resonant triads involving a nondispersive wave
Resonant wave interaction with random forcing and dissipation
Eigenfunctions of linearized integrable equations expanded around an arbitrary
solution
108(1) 2002
Ablowitz MJ. Akylas TR. Lin CC.
Lin CC.
Malkus WVR.
Newell AC.
Diminnie DC. Haberman R.
Grimshaw R. Skyrnnikov Y.
Maslowe SA. Clarke SR.
Rosales RR. Tabak EG. Turner CV.
Milewski PA. Tabak EG. Vanden-Eijnden E.
Yang JK.
Studies in Applied Mathematics
161
187
217
A uniformly valid asymptotic approach to the inviscid-viscous interaction theory
Asymptotic expansions of generalized stieltjes transforms of algebraically decaying functions
Proof of the stokes conjecture in the theory of surface waves
108(2) 2002
Turkyilmazoglu M. Ruban AI.
Lopez JL. Ferreira C.
Plotnikov PI.
Thin-Walled Structures
215
225
239
263
283
297
Analytical solution for forced vibration of a simply-supported v-shaped folded
plate roof
The suitability of round clinching tools for high strength structural steel
Eect of imperfections on numerical simulation of instability behaviour of coldformed steel members
Design procedure for stiened water-lled steel conical tanks
Periodicity in the response of nonlinear plate, under moving mass
Optimization of open cross section of the thin-walled beam with at web and
circular ange
40(3) 2002
Lai YM. Yu WB.
Varis JP.
Dubina D. Ungureanu V.
El Damatty AA. Marroquin E.
Shadnam MR. Rofooei FR. Mod M. Mehri B.
Magnucki K.
Zeitschrift fur Angewandte Mathematik und Mechanik
75
89
101
115
125
137
142
On the asymptotic analysis of discontinuous systems
Low-frequency dispersion-function factorization and classication of p-sv modes
by wavenumber limits
An approximate newton-like coupling of subsystems
Inltration through deformable porous media
A stage structure model for the growth of a population involving switching and
cooperation
Low-frequency penetration of a plane elastic wave through the periodic array of
interface cracks
A note on the free convection from curved surfaces
82(2) 2002
Fidlin A.
Ivansson S.
Menck J.
Ambrosi D.
Khan QJA. Krishnan EV. Al-Lawatia MA.
Ciarletta M. Alexandrov VM. Sumbatyan MA.
Magyari E. Pop I. Keller B.
35
Zeitschrift fur Angewandte Mathematik und Mechanik
147
159
167
177
191
201
207
211
On criteria for asymptotic stability of dierential-algebraic equations
Complex fractional programming involving generalized quasi/pseudo convex functions
Fluid ow with dynamic contact angle: numerical simulation
All about carnot ow
Spectrum modication for gyroscopic systems
On creep rupture of rectangular plates
Bobillier formula as a fundamental law in planar motion
The role of induced air shear on the development of a conducting uid lm over
a rough spinning disk in the presence of a transverse magnetic eld
82(3) 2002
Stykel T.
Lai HC. Liu JC.
Dorer W. Goncharova O. Kroner D.
Forster K.
Datta BN. Ram YM. Sarkissian DR.
Bodnar A. Chrzanowski M.
Fayet M.
Usha R. Uma B.
Zeitschrift fur Angewandte Mathematik und Physik
1
12
20
35
48
58
73
90
103
123
147
160
167
Some blow-up results for a generalized ginzburg-landau equation
Thermal ow through a porous radiant of low conductivity
Spectral stability of small-amplitude shock proles for dissipative symmetric
hyperbolic-parabolic systems
Axisymmetric wake and jet solutions in decelerating streams
Natural convection of uid with variable viscosity from a heated vertical wavy
surface
Boundary slip phenomena in a binary gas mixture
Well-posedness of the dirichlet problem in non-elliptic isotropic elasticity
Elastostatic inverse formulation
Travelling fronts for the kpp equation with spatio-temporal delay
Computation of lyapunov characteristic exponents for continuous dynamical systems
Blow-up in a reactive-diusive medium with a moving heat source
The bailey criterion: statistical derivation and applications to interpretations of
durability tests and chemical kinetics
The motion of two axi-symmetric rigid bodies with friction coupling
53(1) 2002
Aassila M.
Polisevski D.
Humphreys J. Zumbrun K.
Barker J. Wilks G.
Hossain MA. Kabir S. Rees DAS.
Ivchenko IN. Loyalka SK. Tompson RV.
Ernst E.
Xu W. Genin J.
Ashwin P. Bartuccelli MV. Bridges TJ. Gourley SA.
Udwadia FE. von Bremen HF.
Kirk CM. Olmstead WE.
Freed AD. Leonov AI.
Wilms EV. Cohen H.